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OXY-ACETYLENE  WELDING 
PRACTICE 


A  PRACTICAL  PRESENTATION  OF  THE  MODERN  PROCESSES  OF 

WELDING,  CUTTING,  AND  LEAD  BURNING,  WITH  SPECIAL 

ATTENTION  TO  WELDING  TECHNIQUE  FOR  STEEL, 

CAST  IRON,  ALUMINUM,  COPPER,  AND  BRASS 


BY 


ROBERT  J.   KEHL,   M.E. 

M 

CONSULTING   MECHANICAL    ENGINEER,    CHICAGO 

AMERICAN    SOCIETY    OF    MECHANICAL    ENGINEERS 

ASSOCIATE,  AMERICAN  INSTITUTE  OF  ELECTRICAL  ENGINEERS 


ILLUSTRATED 


AMERICAN  TECHNICAL  SOCIETY 

CHICAGO 

1918 


COPYRIGHT,   1917,  BY 

AMERICAN  TECHNICAL  SOCIETY 


COPYRIGHTED  IN  GREAT  BRITAIN 
ALL  RIGHTS  RESERVED 


-  •v1$0"H, 


INTRODUCTION 

HIGH-TEMPERATURE  flames,  such  as  the  oxy-hydrogen 
flame,  were  known  for  many  years,  but  the  oxy-acetylene  flame 
was  first  used  experimentally  in  1901  by  Fouche  and  Picard.  The 
same  experimenters  also  developed  the  first  welding  blowpipes,  used 
industrially  in  1903,  and  started  the  developments  in  oxy-acetylene 
welding  which  were  destined  to  become  so  important  in  the  modern 
manufacturing  and  repair  fields.  Cutting  by  means  of  oxygen 
was  first  made  commercially  possible  in  1905  by  Jottrand,  who  took 
out  his  basic  patent  in  that  year. 

<I  Many  difficulties  were  encountered  in  the  early  development, 
owing  to  imperfect  knowledge  of  the  character  of  the  flame  and  of 
the  technique  of  the  method  of  application,  but  notwithstanding 
these  difficulties,  the  oxy-acetylene  welding  and  cutting  processes 
have  developed  wonderfully,  especially  during  the  last  ten  years, 
during  which  time  they  have  replaced  old  methods  and  have  made 
possible  operations  which  hitherto  could  not  be  accomplished. 
The  discovery  of  liquid  air  greatly  decreased  the  cost  of  oxygen, 
and  the  increase  in  the  number  of  oxygen  supply  points  throughout 
the  country  has  removed  the  last  obstacle  to  the  rapid  advance  of 
the  art.  Everywhere  manufacturers  are  very  willing  to  supplant 
their  old  methods  by  the  oxy-acetylene  process. 

<I  Their  rapid  increase  in  the  number  of  plants  using  the  process 
has  produced  an  active  demand  for  skilled  operators,  a  demand  which 
unfortunately  has  been  always  much  greater  than  the  supply.  How- 
ever, now  that  the  apparatus  on  the  market  has  become  standardized 
and  our  knowledge  of  good  oxy-acetylene  practice  has  reached  a 
point  where  methods  can  be  carefully  outlined,  the  publishers  of  this 
little  volume  feel  that  an  authoritative  article  on  this  subject  will  be 
appreciated  by  the  many  persons  interested  in  the  welding  field.  The 
material  has  been  written  for  the  welding  operator  as  well  as  for  the 
superintendent  and  manager.  The  examples  have  been  taken  from 
the  automobile  industry  because  in  that  field  almost  every  phase  or 
class  of  welding  is  covered,  and  while  the  instructions  and  data  deal 
with  automobile  welding  in  particular,  the  repairman  and  manu- 
facturer will  find  no  difficulty  in  applying  this  information  to  their 
own  particular  needs.  The  publishers  will  be  very  glad  to  give 
special  information  to  any  reader,  either  through  their  own  experts 
or  through  the  help  of  the  author  himself. 


. 


371608 


CONTENTS 

WELDING  PROCESSES 

PAGE 

Oxy-acetylene  process 3 

Advantages 3 

Gases ." 3 

Generators 5 

Welding  blowpipes 7 

Oxy-acetylene  flame 8 

Expansion  and  contraction 8 

Preparation  of  work 8 

Welding  rod : 8 

Flux 9 

Strength  of  weld 9 

Oxy-acetylene  cutting 10 

Electric  processes 11 

Methods 11 

Spot-welder 11 

Arc  welder . .                                                        12 


TECHNIQUE   OF   OXY-ACETYLENE  WELDING 

Simple  welding  job 14 

Apparatus  required 14 

Preparing  the  metal 14 

Connecting  the  apparatus 14 

Welding 15 

Operation  and  care  of  welding  apparatus 16 

Necessity  for  care 16 

Necessary  welding  apparatus 16 

Welding  blowpipe 16 

Regulators 19 

Hose 21 

Instructions  for  connecting  apparatus 22 

i   How  to  light  blowpipe 23 

How  to  shut  off  blowpipe 23 

Back-firing 24 

Character  of  flame 24 

Position  of  blowpipe 27 

Position  of  welding  rod 29 

Haste  fatal  to  good  welding 31 

How  to  weld  up  a  hole 31 

Overhead  and  vertical  welding 31 

Beginning  a  long  weld 31 

Defects  in  welds. .  32 


CONTENTS 

PAGE 

Welding  different  metals 34 

Properties  of  metals 34 

Expansion  and  contraction 36 

Handling  simple  case  of  expansion  and  contraction 37 

Handling  complex  case  of  expansion  and  contraction 39 

Pre-heating 40 

Steel  welding 43 

Cast-iron  welding 59 

Malleable-iron  welding 67 

Aluminum  welding 68 

Copper  welding 72 

Brass  and  bronze  welding 74 

MISCELLANEOUS   OXY-ACETYLENE   PROCESSES 

Cutting 76 

Principle  of  cutting  with  oxygen 77 

Cutting  blowpipe 78 

Regulators 79 

Care  of  apparatus 79 

Instructions  for  connecting  apparatus 79 

How  to  light  blowpipe 79 

To  shut  off  blowpipe 80 

Back-firing 80 

Notes  on  cutting 81 

Lead  burning : . .  .  81 

Different  methods 81 

Lead-burning  apparatus 83 

Operation  of  lead-burning  apparatus 83 

Lead-burning  process 84 

Carbon  removing  by  use  of  oxygen 85 

Old  process  of  removing  carbon 85 

Carbon-removing  apparatus 86 

Burning  out  carbon 86 

EXAMPLES   OF  AUTOMOBILE   REPAIR 

Pressed-steel  parts 87 

Frames 87 

Bodies  and  fenders 89 

Springs 92 

Shafts  and  axles 93 

Axle  housings 94 

Manifolds 94 

Engine  cylinders 95 

Crankcases  and  transmission  cases 97 

COSTS 

Measuring  oxygen  consumption 99 

Measuring  acetylene  consumption 102 


OXY-  ACETYLENE  WELDING 
PRACTICE 


INTRODUCTION 

Welding  Field.  The  welding  process  is  undoubtedly  one  of  the 
greatest  contributors  to  the  efficient  and  economical  manufacture  of 
the  modern  automobile.  It  has  made  possible  higher  standards  of 
body  design  and  may  be  given  almost  exclusive  credit  for  the  light 
weight  and  great  strength  of  the  present-day  motor  car,  producing 
stronger  and  better  working  parts  through  the  use  of  pressed  steel 
instead  of  the  heavy  castings  or  riveted  parts,  such  as  axle  housings, 
Fig.  1,  and  manifolds,  tanks,  bodies,  etc.,  Fig.  2. 

In  the  field  of  automobile  repair  it  is  rapidly  assuming  an  equally 
important  place,  affording  a  quick  and  inexpensive  means  of  perma- 
nent repair  to  parts  no  longer  obtainable  from  the  supply  house  or 
manufacturer  and  permitting  the  building  up  of  weak  parts  or  the 
altering  of  the  chassis,  as  may  be  required.  This  great  adaptability 
of  the  welding  unit  has  made  it  an  essential  part  of  the  equipment  of 
every  efficiently  managed  repair  shop. 

WELDING  PROCESSES 

Old  and  New  Methods.  The  old  systems — blacksmith,  or  forge, 
welding,  and  brazing — are  now  seldom  used  in  automobile  work. 
In  fact,  most  blacksmiths  have  equipped  themselves  to  do  welding  in 
the  modern  way,  using  it  almost  exclusively  for  their  repair  work 
because  it  is  cheaper,  simpler,  more  efficient,  and  can  be  used  on 
materials  which  could  not  be  welded  by  means  of  the  old-style 
methods.  The  modern  systems  of  welding  include  the  flame  and 
electric  processes.  Because  it  is  almost  universally  used  in  repair 
shops,  the  flame  process  and  the  apparatus  required  in  its  use  will 
be  discussed  first.  Several  flame-welding  processes  have,  from  time 
to  time,  been  introduced,  all  utilizing  oxygen  in  combination  with 
some  fuel  gas,  such  as  acetylene,  hydrogen,  city  gas,  natural  gas, 
liquid  gas,  Blau  gas,  carbo-hydrogen,  thermaline,  etc.  Many  enthu- 


OXY-ACKTYLENE   WELDING 


Fig.  1.     Oxy-Acetylene  Welding  in  Manufacture  of  Rear  Axle  Housings 


.Fig.  2.    Oxy-Acetylene  Welding  in  Manufacture  of  Automobile  Bodies 


OXY-ACETYLENE  WELDING  3 

siastic  claims  of  superiority  have  been  made  for  each  of  these  combi- 
nations by  their  advocates. 

OXY=ACETYLENE  PROCESS 

Advantages.  The  easy  control  and  intensity  of  the  heat  devel- 
oped by  the  oxy-acetylene  flame  (approximately  6300°  F.)  and  the 
adequate  supplies  of  carbide  and  dissolved  acetylene  which  are 
maintained  in  every  industrial  center  in  the  United  States  have 
proved  the  greater  desirability,  economy,  and  efficiency  of  the  oxy- 
acetylene  process. 

Another  factor  which  has  contributed  largely  to  the  popularity 
of  the  oxy-acetylene  process  is  the  comparatively  inexpensive  appara- 
tus required  and  the  low  cost  of  its  operation.  Its  speed,  portability, 
and  the  ease  with  which  its  method  of  operation  may  be  learned  by 
any  intelligent  workman  make  it  especially  well  fitted  to  the  need  of 
the  automobile  repair  shop.  Very  seldom  is  any  extensive  disman- 
tling of  parts  necessary  in  making  an  oxy-acetylene  repair  and,  for  this 
reason,  it  simplifies  greatly  the  work  of  the  repair  man. 

Gases.  As  is  generally  known,  two  gases  are  used  in  the  oxy- 
acetylene  process — oxygen  and  acetylene. 

Oxygen.  Oxygen  is  manufactured  from  air  by  liquefaction  or 
from  water  by  electrolysis.  The  former  method  is  by  far  the  greatest 
source  of  supply,  furnishing  practically  all  the  oxygen  used  in  this 
country  and  abroad.  Oxygen  made  by  the  liquid-air  process  can 
contain  only  an  impurity  such  as  nitrogen,  which  cannot  possibly  do 
any  harm.  On  the  other  hand,  oxygen  made  by  the  electrolytic 
method  contains  some  hydrogen,  which  will  render  it  dangerous  to 
handle  if  more  than  two  per  cent  is  present. 

Because  of  the  very  high  cost  of  an  oxygen  plant  and  the  ease 
with  which  an  adequate  supply  of  compressed  gas  may  be  obtained 
from  manufacturers'  supply  stations,  it  has  been  found  impractical 
for  even  the  largest  consumers  to  attempt  the  manufacture  of  their 
own  oxygen. 

Almost  everybody  is  familiar  with  the  appearance  of  the  oxygen 
cylinder,  shown  at  the  right  in  Fig.  3,  which  plays  so  important  a 
part  in  present-day  manufacturing.  These  steel  cylinders  contain 
100  or  200  cubic  feet  of  gas  compressed  to  a  pressure  of  1800  pounds 
per  square  inch.  They  are  furnished  to  the  consumer  without  charge, 


OXY-ACETYLENE   WELDING 


the  customer  paying  only  for  the  oxygen  and  returning  the  cylinder  to 
the  manufacturer  when  the  gas  has  been  exhausted. 

Acetylene.     The  acetylene  may  be  obtained  in  cylinders,  shown  at 
the  left  in  Fig.  3,  containing  100  or  300  cubic  feet,  or,  where  large 

quantities  are  re- 
quired, it  is  generated 
on  the  premises. 
Though  frequently  re- 
ferred to  as  com- 
pressed, the  acetylene 
in  cylinders  is  really 
not  compressed,  but 
is  dissolved  in  a  sol- 
vent which  has  the 
property  of  absorbing 
many  times  its  own 
volume  of  acetylene  as 
pressure  is  applied. 
This  liquid  in  which 
the  gas  is  dissolved  in 
no  way  affects  the  flow 
of  gas  except  when  the 
acetylene  is  drawn  off 
from  the  cylinder  at 
too  rapid  a  rate.  Ex- 
perience has  proved 
that  when  the  gas  is 
used  at  a  rate  greater 
than  one-seventh  the 
capacity  of  the  cylin- 
der per  hour,  the 
solvent  is  very  likely 
to  travel  with  the 
acetylene,  lowering  the 
temperature  of  the  flame  and  thus  hindering  the  work.  To  overcome 
this  difficulty,  where  it  is  necessary  to  supply  gas  at  a  greater  rate, 
several  cylinders  may  be  coupled  to  a  manifold,  or  header,  so  that  the 
total  capacity  is  at  least  seven  times  their  hourly  discharge. 


Fig.  3.     Welding  Unit  for  Use  with  Acetylene  in  Cylinders, 

Mounted  on  Emergency  Truck 
Courtesy  of  Oxwdd  Acetylene  Company,  Chicago,  Illinois 


OXY-ACETYLENE   WELDING  5 

Generators.  By  means  of  the  acetylene  generator  it  is  possible 
to  produce  pure  acetylene  at  less  than  half  the  cost  of  dissolved  acety- 
lene, so  that  if  any  considerable  work  is  to  be  done  a  generator 
will  pay  for  itself  within  a  few  months  or  a  year.  In  these  generators 
small  quantities  of  calcium  carbide  are  automatically  fed  into  a  large 


Fig.  4.     Low-Pressure  Acetylene  Generator 
Courtesy  of  Oxweld  Acetylene  Company,  Chicago,  Illinois 

quantity  of  water,  producing  the  gas  at  just  the  rate  required  by  the 
work  in  hand. 

There  are  two  recognized  systems  of  generating  acetylene — 
the  low-pressure  system  and  the  pressure  system. 

Low-Pressure  Generator.  This  type  of  generator,  Fig.  4,  delivers 
acetylene  to  the  blowpipe  under  a  pressure  of  less  than  one  pound. 
This  system  has  the  advantage  of  maintaining  at  all  times  an  abso- 


6 


OXY-ACETYLENE  WELDING 


lutely  constant  pressure,  which  is  an  essential  requirement.  The 
carbide  feed  is  controlled  by  the  rise  and  fall  of  the  gas  bell,  in  which 
the  pressure  is  always  the  same,  without  the  use  of  any  pressure- 
regulating  device. 

Pressure  Generator.  The  pressure  generator,  Fig.  5,  delivers 
acetylene  at  a  pressure  of  more  than  one  pound.  The  carbide  feed  is 
controlled  by  the  pressure  in  the  generator.  As  the  acetylene  is 
drawn  off  and  the  pressure  decreases,  carbide  is  fed  into  the  water; 


Fig.  5.     Portable  Pressure  Acetylene  Generator 
Courtesy  of  Oxweld  Acetylene  Company,  Chicago,  Illinois 

the  generation  of  gas  increases  the  pressure  and  the  feeding  stops. 
In  order  to  compensate  for  this  pressure  variation,  a  pressure-dia- 
phragm regulator,  or  reducer,  is  necessary  so  that  the  acetylene  may 
be  supplied  to  the  blowpipe  at  a  constant  pressure. 

The  low-pressure  generator  furnishes  the  most  satisfactory 
service  under  average  conditions,  though  where  portability  is  essen- 
tial, pressure  generators  of  compact  construction  may  be  obtained  to 
meet  this  need. 


OXY-ACETYLENE   WELDING  7 

Welding  Blowpipes.  There  are  two  types  of  oxy-acetylene 
welding  blowpipes,  namely,  the  low-pressure,  or  injector  type  and 
the  equal-pressure  type. 


Fig.  6.     Oxy-Acetylene  Welding  Blowpipe 
Courtesy  of  Oxwdd  Acetylene  Company,  Chicago,  Illinois 

Injector  Blowpipe.  In  the  injector  type,  Fig.  6,  the  acetylene  is 
delivered  to  the  blowpipe  at  a  pressure  of  only  a  few  ounces.  The 
oxygen  at  a  higher  pressure  passes  through  the  injector,  Fig.  7,  and 
expands  rapidly  into  the  mixing  chamber.  This  rapid  expansion 
and  high  velocity  of  the  oxygen  form  a  suction  and  draw  in  the  acety- 
lene at  a  constant  ratio.  A  slight  variation  in  pressure  of  either 


Fig.  7.     Section  of  Injector-Type  Blowpipe 

the  oxygen  or  acetylene  is  automatically  taken  care  of  by  the  injector, 
so  that  a  neutral  flame  is  maintained  at  all  times. 

Pressure  Blowpipe.  In  this  blowpipe  the  acetylene  is  used  at 
almost  the  same  pressure  as  the  oxygen.  The  oxygen  enters  the 
mixing  chamber  at  the  rear  and  the  acetylene  through  a  couple  of 
holes  at  the  side. 


Fig.  8.     Section  of  Pressure-Type  Blowpipe 

In  the  injector  blowpipe  the  rapid  expansion  into  the  tapered 
mixing  chamber  sets  up  a  whirling  action  and  produces  an  intimate 
mixture  of  the  oxygen  and  acetylene  so  that  a  ratio  of  1.05  parts 
oxygen  to  1,00  part  acetylene  is  obtained,  which  is  almost  the  theo- 


8  OXY-ACETYLENE  WELDING 

retical  or  perfect  ratio  of  1 .00  to  1 .00.  In  the  pressure  blowpipe  there 
is  no  means  of  obtaining  such  an  intimate  mixture  of  the  gases  in  the 
mixing  chamber,  Fig.  8,  which  in  most  cases  is  not  tapered,  and  con- 
sequently about  the  best  ratio  obtainable  is  1.14  to  1.00.  This  larger 
amount  of  oxygen  is,  of  course,  wasted  and,  besides,  tends  to  produce 
an  oxidized  weld.  It  is  the  surface  oxidation,  or  burning,  of  the 
molten  metal  that  leads  some  operators  to  believe  that  they  are 
welding  fast,  while  in  reality  they  are  only  burning  the  surface  and  are 
not  fusing  the  metal  underneath. 

Oxy=Acetylene  Flame.  The  oxy-acetylene  flame  is  the  hottest 
flame  obtainable.  Its  temperature  of  6300°  F.  is  2000  degrees  above 
that  of  any  of  the  other  flames.  This  high  temperature  allows  the 
work  to  be  done  quickly  and  with  only  a  very  slight  loss  of  heat  due 
to  conduction  and  radiation. 

There  are  three  phases  of  the  oxy-acetylene  flame,  Fig.  18, 
namely,  the  neutral,  or  welding,  flame;  the  carbonizing,  or  reducing, 
flame;  and  the  oxidizing  flame.  Each  of  these  has  its  characteristic 
appearance  and  it  takes  only  a  little  practice  to  instantly  recognize 
them.  The  appearance  of  these  will  be  taken  up  later  under  "Flame 
Regulation",  page  25. 

Expansion  and  Contraction.  These  natural  changes  of  the  work, 
due  to  the  heat  of  the  welding,  are  taken  care  of  in  the  case  of  rolled  or 
forged  materials  by  proper  spacing  of  the  edges  or  by  holding  the  work 
in  suitable  jigs  and,  in  the  case  of  castings,  by  proper  pre-heating  and 
cooling.  The  most  satisfactory  methods  of  handling  this  feature  will 
be  taken  up  under  the  instructions  for  welding  various  materials. 

Preparation  of  the  Work.  This  is  a  very  important  feature  and 
should  receive  the  operator's  best  thought  and  effort.  A  fair  amount 
of  reasoning  and  planning  on  the  part  of  the  operator  before  he 
attempts  a  job  will  save  considerable  time  and  keep  the  cost  of  the 
welding  low.  The  operator  should  figure  out  several  ways  and  means 
of  handling  the  particular  task  at  hand,  and  should  then  select  the 
best.  This  applies  especially  to  castings,  such  as  crankcases  and 
cylinders,  which  may  be  welded  perfectly  if  the  operator  uses  good 
judgment  but  which  will  be  ruined  if  he  does  not. 

Welding  Rod.  Thin  plates  may  be  welded  by  bringing  the  edges 
into  contact  and  fusing  them  together.  For  heavier  work,  the  edges 
are  beveled  to  form  a  groove,  and  a  filling  material,  or  "welding- 


OXY-ACETYLENE  WELDING  9 

rod",  is  fused  into  the  groove.  In  most  cases  a  material  similar  to 
the  work  being  welded  is  used.  The  operator  may  build  up  the  weld 
by  means  of  the  welding  rod  so  that  the  section  at  the  weld  is  greater 
than  the  section  before  welding,  thus  insuring  a  strength  even  greater 
than  the  rest  of  the  piece. 

Flux.  A  suitable  flux  is  used  in  cast  iron,  aluminum,  brass, 
•copper,  etc.,  welding  to  dissolve  any  impurities  and  to  give  a  film, 
or  protecting  coating,  to  the  fused  material  to  prevent  oxidation. 

Both  the  welding  rod  and  the  flux  used  are  extremely  Important 
factors  in  the  welding  and  should  be  obtained  from  a  reliable  manu- 
facturer who  supplies  only  materials  that  are  tested  and  analyzed  to 
determine  their  purity  and  suitability  for  the  work. 

Strength  of  Weld.  With  proper  equipment  and  suitable  rods 
and  fluxes,  the  strength  of  the  weld  will  depend  mainly  upon  the  skill 


Fig.  9.     Oxy-Acetylene  Cutting  Blowpipe 
Courtesy  of  Oxweld  Acetylene  Company,  Chicago,  Illinois 

and  care  of  the  operator.  An  operator  who  has  had  considerable 
experience  and  who  is  careful  with  his  work  should  be  able  to  obtain 
as  high  as  95  per  cent  the  strength  of  the  original  material,  although  85 
per  cent  may  be  taken  as  a  safe  lower  limit  for  the  average  good  welder. 

Working  and  Hammering.  If  the  weld  is  hammered  when  at 
the  proper  temperature,  its  strength  will  be  increased,  in  the  case  of 
welds  in  steel,  by  making  the  grain  of  the  material  finer. 

Experience  of  Operator.  Poor  work  due  to  carelessness  or 
inexperience  of  the  operator,  poorly  designed  and  cheaply  constructed 
apparatus  that  is  not  capable  of  handling  the  work,  may  be  held 
responsible  for  such  failures  as  may  occur  in  the  oxy-acetylene  process. 

The  handling  of  the  process  is  not  difficult  and,  therefore,  some 
operators  undertake  difficult  jobs  before  they  are  sufficiently  capable 
or  experienced.  When  such  a  job  fails,  it  is  but  natural  that  both  the 


10 


OXY-ACETYLENE  WELDING 


customer  and  the  operator  should  blame  the  process  rather  than  the 
way  in  which  the  work  was  handled.  Time  may  be  very  profitably 
spent  in  practice  on  scrap  material  before  undertaking  work  on  mate- 
rials with  which  the  operator  is  unfamiliar.  By  thus  laying  the 
foundation  for  a  satisfactory  result,  the  operator  may  quickly  develop 


Fig.  10.     Electric  Spot- Welding  Machine 
Courtesy  of  Thomson  Spot  Welder  Company,  Cincinnati,  Ohio 

his  skill  to  the  point  which  will  bring  him  the  confidence  and  patron- 
age of  a  constantly  increasing  number  of  customers. 

Oxy=Acetylene  Cutting.  Cutting  by  the  oxy-acetylene  process 
is  done  by  means  of  a  separate  blowpipe,  Fig.  9,  quite  different  in 
construction  from  that  used  for  welding.  A  more  detailed  description 
of  the  cutting  process  is  given  on  page  77. 


OXY-ACETYLENE  WELDING 


11 


ELECTRIC  PROCESSES 

Methods.     For  a  number  of  years  electric  welding  was  used  as  a 
,    laboratory  experiment,  but  recently  the  process  has  been  more  fully 
/    developed.     Two  distinct  methods  are  utilized:  one,  the  electric- 
resistance  welder,  or  spot- welder,  Fig.  10;  and  the  other,  the  electric- 
arc  welding  machine,  Fig.  11. 

Spot=Welder.  The  electric-resistance  welding  process  provides 
for  the  passage  of  a  heavy  current  through  the  joint  between  the 
pieces  to  be  welded,  allowing  the  resistance  of  the  bad  contact  to  heat 
them  locally  until  they  are  soft  enough  to  stick  together;  squeezing 


Fig.  11.     Portable  Arc-Welding  Outfit 
Courtesy  of  C  &  C  Electric  and  Manufacturing  Company,  Garwood,  New  Jersey 

the  pieces  while  soft  will  then  cause  them  to  adhere.  This  process  is 
used  mostly  in  making  light  automobile  parts,  such  as  mud  guards, 
bonnets,  etc.,  rather  than  for  repair.  It  is  also  used  to  some  extent 
instead  of  small  rivets  in  light  sheet-metal  work  and  for  spotting,  or 
tacking,  small  parts  together  preparatory  to  welding  them  with  the 
oxy-acetylene  flame. 


12 


OXY-ACETYLENE  WELDING 


Arc  Welder.  In  order  to  do  welding  with  the  electric  arc,  after 
suitable  equipment  has  been  provided,  it  is  necessary  to  first  connect 
the  work  to  the  positive  side  of  the  power-supply  circuit  and  the 
welding  electrode  to  the  negative  side  of  the  circuit  by  means  of  wires 
or  cables,  with  the  regulating  devices  in  circuit  to  control  the  amouut 
of  current  flowing.  tlie  negative  electrode  is  then  placed  lightly  in 
contact  with  the  wdrk  and  quickly  withdrawn  to  make  the  circuit 


Fig.  12.     Operator  Using  Metallic  Electrode 
Courtesy  of  C  &  C  Electric  and  Manufacturing  Company,  Garwood,  New  Jersey 

and  draw  the  arc,  thus  providing  the  high  temperature  required  for 
welding. 

Electric-arc  welding  usually  consists  in  using  the  heat  of  the  arc 
to  fuse,  or  melt,  the  filling  material  into  the  place  to  be  filled,  although 
the  article  worked  upon  may  be  melted  down  sufficiently  to  fill  the 
space  if  it  is  large  enough  at  the  point  to  be  welded. 

Two  methods,  or  processes,  using  the  arc  for  welding,  are  in 
commercial  use,  these  being  the  metallic  and  the  graphite,  or  carbon, 
processes. 


OXY-ACETYLENE  WELDING 


13 


Metallic  Electrode.  The  metallic  welding  process  consists  in  using 
a  piece  of  wire  of  the  proper  kind  as  the  negative  electrode  of  the  arc 
and  fusing  it  into  place,  drop  by  drop,  Fig.  12. 

Graphite  Electrode.  The  graphite  process  consists  in  using  a  piece 
of  graphite,  or  carbon,  as  the  negative  electrode  and  fusing  a  piece  of 
metal  into  place  by  the  heat  of  the  arc. 

Apparatus.  It  is  possible,  though  not  practical,  to  do  electric- 
arc  welding,  having  nothing  but  a  source  of  primary  current,  and  some 


SEKIES  RELAY 


WORK  4- 
Fig.  13.     Wiring  Diagram  for  C  &  C  Welding  System 

means  for  regulating  the  amount  of  current  flowing,  but  the  use  of 
resistance  only  as  a  means  of  regulating  the  amount  of  current  flow  is  so 
wasteful  that  other  apparatus  must  be  used  for  the  sake  of  economy. 
It  is  well  known  among  electrical  men  that  a  motor-generator  set 
gives  the  best  regulation  of  voltage,  therefore,  the  leading  arc-welding 
outfits  in  use  today  consist  of  a  motor-generator  set  with  suitable 
rheostats,  resistances,  circuit-breakers,  fuses,  indicating  instruments, 
and  switches  for  controlling  the  motor-generator  and  welding  cir- 
cuits, Fig.  13. 


14  OXY-ACETYLENE  WELDING 

From  the  foregoing  description,  it  will  be  surmised  that  an  electric- 
arc  welding  equipment  will  be  too  expensive  in  initial  cost  for  the 
average  auto  repair  shop.  However,  it  finds  a  useful  field  in  the 
welding  of  very  heavy  work  where  there  is  sufficient  volume  of  it  to 
justify  the  investment. 

TECHNIQUE  OF  OXY-ACETYLENE  WELDING 

SIMPLE  WELDING   JOB 

Apparatus  Required.  The  material  in  the  following  paragraphs 
must  not  be  considered  as  instructions  for  welding  but  merely  as  a 
brief  discussion  of  the  various  steps  in  making  a  simple  weld.  Com- 
plete instructions  for  connecting  and  operating  the  equipment  are 
given  in  detail  later.  In  general,  the  following  equipment  is  needed 
for  every  welding  job,  no  matter  how  small: 

(a)  A  welding  blowpipe 

(b)  A  supply  of  oxygen 

(c)  An  oxygen  regulator 

(d)  A  supply  of  acetylene 

(e)  An  acetylene  regulator 

(f)  Hose  to  connect  blowpipe  to  oxygen  and  acetylene  supplies 
Preparing  the  Metal.    First,  the  edges  of  the  two  pieces  of  metal 

to  be  welded  are  chamfered  or  beveled,  so  that  when  they  are  placed 
together  the  two  beveled  edges  form  a  V,  the  width  of  the  V  being 
about  equal  to  the  thickness  of  the  metal. 

Next,  the  two  pieces  are  placed  together  on  a  flat  surface  of  fire 
brick,  or  other  nonconductor  of  heat,  so  that  the  edges  just  touch  at 
the  bottom  of  the  groove.  This  gives  the  line  of  the  weld.  The  two 
pieces  are  then  ready  to  be  welded  as  soon  as  the  apparatus  is  con- 
nected. 

Connecting  the  Apparatus.  To  connect  the  apparatus,  the 
following  steps  should  be  taken: 

(1)  The  oxygen  regulator  is  connected  to  the  oxygen  cylinder. 

(2)  The  acetylene  regulator  is  connected  to  the  acetylene  cylinder. 

(3)  The  one  hose  is  connected  to  the  oxygen  regulator  and  to  the 

blowpipe. 

(4)  The  other  hose  is  connected  to  the  acetylene  regulator  and  to  the 

blowpipe. 


OXY-ACETYLENE  WELDING  15 

(5)  A  welding  head  is  selected  and  attached  to  the  blowpipe. 

(6)  The  oxygen  and  acetylene  are  turned  on  and  the  blowpipe  is 

lighted. 

Welding.  The  operator  is  now  ready  to  weld.  He  takes  the 
lighted  blowpipe  in  his  right  hand,  Fig.  14,  and  plays  the  flame  upon 
the  beveled  edges  of  the  two  pieces  of  metal  to  be  welded.  The 
intense  heat  of  the  flame  melts  the  edges  and  they  flow  together.  As 


Fig.  14.     Simple  Job  of  Welding 

the  edges  flow  together,  the  operator  melts  in  new  metal  from  a  rod 
which  he  holds  in  his  left  hand,  so  that  the  entire  goove  is  filled  up, 
producing  a  perfect  union  or  weld. 

When  the  entire  groove  has  been  filled  in  this  manner,  the 
operator  turns  out  the  blowpipe,  and  allows  the  metal  to  cool. 

The  foregoing  is  a  brief  outline  of  the  steps  taken  by  an  operator 
in  performing  a  simple  operation  of  welding  two  small  pieces  of  steel. 

We  will  now  take  up  these  different  steps  and  will  give  more 
specific  and  detailed  descriptions  of  the  welding  apparatus  and  com- 
plete instructions  in  its  operation  and  use. 


16  OXY-ACETYLENE  WELDING 

OPERATION  AND  CARE  OF  WELDING  APPARATUS 

Necessity  for  Care.  It  is  proper  that  in  the  operation  of  the 
welding  apparatus  we  should  lay  stress  upon  the  importance  of  careful 
and  orderly  methods  in  the  handling  of  such  apparatus.  It  should 
be  borne  in  mind  that  the  regulators  and  gages  are  sensitive  measuring 
devices,  that  in  the  blowpipe  the  orifices  are  carefully  designed  and 
accurately  machined  to  permit  the  passage  of  a  definite  quantity  of 
gas  and,  therefore,  that  rough  usage  and  abuse  will  certainly  decrease 
their  efficiency.  It  is  not  necessary  in  this  place  to  give  detailed 
instructions  for  the  operation  and  care  of  the  various  makes  of  appara- 
tus, because  these  are  invariably  furnished  by  the  manufacturers  with 
their  equipment. 

Because  of  the  fact  that  dissolved  acetylene  is  most  generally 
used  in  garages  and  small  job  shops,  we  will  confine  our  explanations 
to  the  use  of  apparatus  with  cylinder  equipment.  Owing  to  the 
greater  simplicity  of  handling,  however,  the  operator  will  have  no 
difficulty  in  making  use  of  generated  acetylene  when  the  opportunity 
arises. 

Necessary  Welding  Apparatus.  A  complete  welding  station, 
Fig.  15,  for  use  with  acetylene  dissolved  in  cylinders,  consists  of  the 
following  apparatus: 

Welding  blowpipe  G  with  set  of  welding  heads 

Oxygen  welding  regulator  C  with  two  gages 

Acetylene  regulator  D  with  one  or  two  gages 

Adapter  L  for  acetylene  cylinder 

Two  lengths  high-pressure  hose  E  and  F 

Darkened  spectacles,  wrenches,  hose  clamps,  etc. 

Welding  Blowpipe.  The  two  types  of  welding  blowpipes  were 
described  on  pages  7  and  8,  and  need  no  further  explanation  as  to 
the  principles  of  operation.  They  are  furnished  by  the  manufacturers 
in  various  lengths  to  take  care  of  various  classes  of  work,  from  short 
light-weight  blowpipes  less  than  a  foot  long  for  light  sheet-metal  work 
up  to  blowpipes  several  feet  long,  which  allow  the  operator  to  stay 
away  from  the  intense  heat  as  far  as  possible  when  working  on  heavy 
jobs. 

Welding  Heads  and  Tips.  About  ten  sizes  of  welding  heads, 
or  tips,  are  supplied  for  use  on  different  thicknesses  of  metal  and  vari- 
ous classes  of  work,  each  giving  its  own  special  size  flame.  The 


OXY-ACETYLENE   WELDING 


17 


oxygen  consumption  of  the  various  size  heads  ranges  from  about  4  to 
70  cubic  feet  per  hour.     In  some  makes  the  heads  are  made  of  one 


Fig.  15.     Complete  Welding  Station 

piece,  while  in  others  they  consist  of  a  brass  or  bronze  body  and  a 

copper  tip,  which  can  be  easily  and  cheaply  replaced  when  necessary. 

Working  Pressures.     The  necessary  pressures  of  the  gas  that  are 

required  by  the  different  size  welding  heads  are  given  by  the  manufac- 


18 


OXY-ACETYLENE   WELDING 


turers,  and  it  is  very  important  that  the  operator  use  only  the  pres- 
sures recommended  if  he  wishes  to  get  the  best  economy  and  the 
strongest  weld  possible.  Some  operators  believe  that  by  increasing 
the  pressure  above  that  specified  by  the  maker  of  the  apparatus  that 
they  are  able  to  do  the  work  more  quickly  and  easily.  This  idea  is 
wrong,  because  when  the  pressure  is  increased,  the  larger  volumes  of 
oxygen  and  acetylene  cannot  mix  as  well,  so  that  oxide  forms  in  the 
weld  and  has  to  be  removed.  This  takes  more  time  and  is  very  likely 
to  leave  a  slightly  oxidized  and  weak  weld. 

If  the  welding  head  being  used  is  not  large  enough,  use  a  larger 
size;  never  try  to  increase  the  ability  of  the  smaller  head  by  increasing 

the  pressure. 

It  is  equally  bad  to  use  a  pres- 
sure that  is  too  low.  If  this  is  done, 
continual  back-firing  will  result. 

Care  of  Blowpipe.  If  the  blow- 
pipe is  handled  properly  there  will 
be  very  little  deterioration.  It 
should  only  be  necessary  to  clean 
the  replaceable  and  working  parts 
and  occasionally  ream  out  the  tips. 
The  tips  should  never  be 
reamed  out  with  any  instrument 
other  than  a  copper  or  brass  wire 
having  a  long  taper.  Care  should 
be  taken  that  the  orifices  of  the  tips  are  not  enlarged  by  reaming. 
If  they  become  enlarged,  they  may  be  closed  slightly  by  placing  a 
conical  swag  over  the  end  and  tapping  lightly  with  a  hammer.  The 
end  of  the  tip  should  then  be  dressed  off  square  by  means  of  an 
extra  fine  file,  and  the  orifice  trued  round  by  reaming  with  a  twist 
drill  of  the  proper  size. 

The  blowpipe  may  be  cleaned  by  removing  both  the  acetylene 
and  the  oxygen  hose  and  connecting  the  tip  to  the  oxygen  hose. 
Fig.  16,  and  turning  on  the  oxygen  to  a  pressure  of  about  20  pounds 
per  square  inch,  having  the  acetylene  needle  valve  open  and  the  oxygen 
needle  valve  closed,  so  as  to  drive  any  obstructions  through  the  larger 
acetylene  passages  of  the  blowpipe.  Then  close  the  acetylene  valve 
and  open  the  oxygen  valve  to  clean  out  the  oxygen  passages. 


Fig.  16.     Cleaning  Blowpipe  by  Means  of 
Oxygen  under  Pressure 


OXY-ACETYLENE   WELDING 


19 


Regulators.  There  are  various  types  of  regulators  on  the 
market  today,  but  the  most  successful  ones  are  very  similar  in  design 
and  construction.  The  principal  parts  of  a  constant-pressure  regu- 
lator, Fig.  17,  consist  of  the  body  proper,  regulator  valve,  diaphragm, 
pressure-adjusting  spring,  safety-relief  valve,  and  gages. 

The  diaphragm  may  be  either  special  reinforced  rubber  sheeting 
or  phosphor  bronze.  The  former  is  preferred,  because  it  is  less  likely 
to  crack,  or  split,  is  more  readily  replaced,  and  gives  more  sensitive 
regulation  because  of  its  finer  elastic  properties. 


Fig.  17.     Section  of  Pressure  Regulator 
Courtesy  of  Oxweld  Acetylene  Company,  Chicago,  Illinois 

Operation  of  the  Regulator.  Gas  passes  from  the  cylinder  valve 
through  the  passageway  to  the  regulator  valve.  The  pressure  over- 
comes the  tension  of  the  inner  spring  and  moves  the  sleeve-piece 
toward  the  back  of  the  regulator,  opening  the  valve.  This  allows  gas 
to  pass  into  the  diaphragm  chamber  and  out  of  the  regulator  by  way 
of  the  hose  connection.  As  the  pressure  in  the  diaphragm  chamber 
increases,  the  tension  of  the  pressure-adjusting  spring  is  overcome, 
the  diaphragm  deflects,  the  sleeve-piece  moves  forward,  and  the  valve 


20  OXY-ACETYLENE  WELDING 

closes  partly  or  all  the  way.  Then,  as  gas  passes  out  of  the  regulator 
and  the  pressure  in  the  diaphragm  chamber  decreases,  the  tension 
of  the  pressure-adjusting  spring  and  the  pressure  of  the  gas  entering 
the  regulator  move  the  sleeve-piece  backward,  admitting  more  oxygen 
to  the  regulator.  The  pressure  in  the  diaphragm  chamber  builds  up 
as  before,  the  diaphragm  deflects,  the  sleeve-piece  moves  outward, 
and  the  valve  closes. 

Oxygen  Welding  Regulator.  This  is  an  automatic  regulator 
which  is  especially  designed  for  welding  operations.  It  is  connected 
to  the  oxygen  cylinder  and  is  designed  to  deliver  oxygen  to  the  blow- 
pipe at  any  uniform  pressure  at  which  the  regulator  is  set.  To  do 
successful  welding,  the  oxygen  regulator  must  be  as  nearly  perfect  as 
it  is  possible  to 'construct  it.  This  device  is  required  to  reduce  a 
pressure  which  may  be  as  high  as  1800  pounds  per  square  inch  in 
the  cylinder  and  which  is  constantly  varying,  down  to  a  pressure 
from  10  to  30  pounds  per  square  inch;  at  the  same  time  the  regulator 
must  keep  the  lower  pressure  constant. 

Oxygen  regulators  are  usually  equipped  with  two  gages.  The 
high-pressure  gage  shows  the  pressure  of  the  gas  in  the  cylinder  and 
may  be  used  to  determine  the  amount  of  oxygen  in  the  cylinder  (see 
under  Measuring  Oxygen,  page  99).  The  low-pressure  gage  shows 
the  operating  pressure  at  which  the  oxygen  is  being  supplied  to  the 
blowpipe. 

Acetylene  Regulator.  The  acetylene  regulator  is  used  with 
acetylene  supplied  in  cylinders.  It  is  connected  to  the  acetylene 
cylinder  adapter,  and  this  to  the  acetylene  cylinder.  The  acetylene 
regulator  is  designed  to  deliver  acetylene  at  a  uniform  pressure,  as 
needed  by  the  blowpipe. 

Acetylene  regulators  are  usually  equipped  with  a  large  gage  that 
shows  the  pressure  in  the  cylinder,  but  which  cannot  be  used  to 
accurately  determine  the  contents  of  the  cylinder  (see  Measuring 
Acetylene,  page  102) .  A  small  gage  is  not  necessary  with  the  low- 
pressure,  or  injector,  blowpipe,  because  the  acetylene  pressure  required 
by  this  type  of  blowpipe  is  very  low — only  a  few  ounces.  With  the 
pressure  blowpipe,  however,  a  small  gage  is  necessary,  because  it  is 
important  to  know  that  the  acetylene  pressure,  which  ranges  from  2 
to  13  pounds  per  square  inch,  is  supplied  to  the  blowpipe  at  the 
required  pressure  for  the  tip  used. 


OXY-ACETYLENE  WELDING  21 

Care  of  Regulators.  Never  drop  or  jar  a  regulator.  Do  not  use  oil, 
grease,  or  any  organic  material  for  lubrication  in  connection  with  regu- 
lator. If  it  becomes  necessary  to  lubricate  the  pressure-adjusting 
screw,  or  to  repack  a  needle  valve,  make  use  of  a  little  glycerine — 
nothing  else. 

Do  not  allow  dust  to  enter  the  regulator.  Always  insert  the 
dust  plug  when  the  regulator  is  not  in  use.  These  are  supplied  with 
most  regulators  and  are  intended  to  keep  dust  out  of  the  regulator 
when  it  is  not  in  use  and  to  protect  the  union  nipple  at  the  back. 

Do  not  change  the  regulator  from  one  cylinder  to  another  without 
releasing  the  pressure-adjusting  screw.  The  diaphragm  is  liable  to  be 
ruptured  if  there  is  tension  on  it  when  the  sudden  rush  of  gas  takes 
place  as  the  cylinder  valve  is  opened. 

Do  not  attempt  to  repair,  adjust,  or  change  the  internal  mechan- 
ism of  the  regulator,  other  than  replacing  the  diaphragm  and  resurfac- 
ing or  replacing  the  valve  seat.  Send  it  to  the  manufacturer  for 
repairs. 

Do  not  replace  diaphragms  or  valve  seats  with  any  material 
other  than  that  supplied  by  the  manufacturer  for  this  purpose. 

Hose.  The  best  hose  that  it  is  possible  to  obtain  should  be  used, 
because  it  is  really  the  most  economical  in  the  end,  although  it  might 
cost  more  at  the  beginning.  A  good  grade  of  two-ply  hose  will  be 
found  to  be  flexible,  light  weight,  easy  to  handle,  and,  at  the  same 
time,  will  not  kink  easily  nor  be  permanently  flattened  if  heavy 
objects  happen  to  accidentally  fall  on  it.  In  selecting  a  hose,  the 
welder  should  see  that  he  gets  a  hose  that  has  a  finished  inside  surface, 
so  that  small  particles  of  rubber  and  dust  will  not  flake  off  and  be 
blown  into  and  clog  the  blowpipe  or  welding  head. 

It  is  best  to  use  different  colored  hose  for  the  oxygen  than  for 
the  acetylene  to  prevent  errors  in  connecting  and  to  avoid  any  pos- 
sible danger  from  interchanging. 

Care  of  Hose.  Both  the  acetylene  and  the  oxygen  hose  should  be 
blown  out  occasionally  so  that  dirt  and  dust  will  not  be  carried  into 
the  blowpipe.  This  can  be  done  by  removing  the  hose  from  the 
blowpipe,  connecting  each  in  turn  to  the  oxygen  regulator,  and 
allowing  oxygen  of  about  20  pounds  per  square  inch  to  blow  through 
it.  Examine  the  hose,  from  time  to  time,  for  leaks  by  immersing  in 
water  when  under  pressure. 


22  OXY-ACETYLENE  WELDING 

INSTRUCTIONS  FOR  CONNECTING  APPARATUS 
Preliminary  Operations.     The  following  directions  are  given 
as  a  starting  point  for  beginners  in  the  operation  of  welding  equipment. 
The  letters  given  refer  to  the  labeled  parts  in  Fig.  15,  page  17. 

1.  First  open  the  oxygen  cylinder  valve  B  for  a  moment  to 
blow  out  any  dirt  or  dust  which  may  have  collected  in  the  valve,  so 
that  it  cannot  enter  the  oxygen  regulator  when  it  is  attached  to  the 
cylinder. 

2.  Remove  the  regulator  dust  plug  and  attach  the  oxygen 
regulator  C  to  the  oxygen  cylinder  A. 

3.  Connect  the  oxygen  hose  E  to  the  oxygen  regulator  and  to 
the  oxygen  hose  connection  on  the  blowpipe  G.    The  hose  connec- 
tions are  usually  readily  distinguished  by  markings  on  the  needle 
valves. 

4.  Release  the  pressure-adjusting  screw  on  the  oxygen  regulator 
by  turning  to  the  left  until  it  is  perfectly  free. 

Do  not  open  the  valve  on  the  oxygen  cylinder  until  positive  that 
the  adjusting  screw  on  the  regulator  is  fully  released.  The  diaphragm 
may  be  ruptured  and  the  regulator  put  out  of  commission. 

5.  Slowly  open  the  oxygen  cylinder  valve  B  as  far  as  it  will  go. 
Not  part  way. 

Do  not  leave  the  valve  on  the  oxygen  cylinder  only  part  way  open. 
This  valve  seats  when  fully  opened  or  closed,  but  is  likely  to  leak  when 
open  only  part  way. 

Do  not  handle  the  regulator  with  greasy  hands  nor  allow  any  oil, 
soap,  or  organic  matter  to  come  in  contact  with  any  part  of  the  regu- 
lator or  cylinder  valve.  Oxygen  under  high  pressure  coming  in  con- 
tact with  these  substances  is  dangerous. 

6.  Wipe  out  the  acetylene  cylinder  valve  to  remove  any  dirt 
or  dust  which  may  have  collected  in  the  valve,  so  that  it  cannot  enter 
the  acetylene  regulator  when  it  is  attached  to  the  cylinder. 

7.  Attach  the  adapter  L  to  the  acetylene  cylinder  K. 

8.  Remove  the  regulator  dust  plug  and  attach  the  acetylene 
regulator  D  to  the  adapter. 

9.  Connect  the  acetylene  hose  F  to  the  acetylene  regulator  and 
to  the  acetylene  hose  connection  on  the  blowpipe  G. 

10.      Release  the  pressure-adjusting   screw   on   the   acetylene 
regulator  by  turning  to  the  left  until  it  is  perfectly  free. 


OXY-ACETYLENE  WELDING  23 

11.  Open  the  acetylene  cylinder  valve  about  three  full  turns  by 
means  of  the  wrench  J. 

12.  Select  the  welding  head  of  the  size  suitable  for  the  work  in 
hand.     Screw  the  welding  head  down  firmly,  but  not  too  tightly,  into 
the  head  of  the  blowpipe  with  the  wrench  provided  for  that  purpose. 

Starting  the  Work 

How  to  Light  the  Blowpipe.  1.  Take  the  blowpipe  in  hand  and 
open  the  oxygen  needle  valve  fully. 

2.  Turn  the  oxygen  pressure-adjusting  screw  to  the  right  until 
the  required  pressure  for  the  welding  head  being  used  shows  on  the 
low-pressure  gage.    See  the  maker's  chart  for  the  correct  pressure. 

3.  Close  the  oxygen  needle  valve. 

4.  Open  the  acetylene  needle  valve  fully. 

5.  Turn  the  acetylene  pressure-adjusting  screw  to  the  right  until 
a  good  jet  of  acetylene  issues  from  the  welding-head  orifice.     In  the 
case  of  pressure  blowpipes,  turn  the  screw  until  the  required  pressure 
for  the  welding  head  being  used  shows  on  the  low-pressure  gage.     (See 
the  maker's  chart  for  the  correct  pressures). 

6.  Open  the  oxygen  needle  valve  slightly  and  light  the  blowpipe 
by  means  of  the  pyro-lighter  that  is  usually  furnished.  , 

7.  Open  the  oxygen  needle  valve  fully. 

NOTE  :  A  back-fire  might  occur  when  turning  on  the  oxygen  if  there  is  not 
enough  acetylene  being  supplied.  If  this  occurs,  increase  the  acetylene  supply 
by  turning  the  acetylene  pressure-adjusting  screw  farther  to  the  right. 

8.  Adjust  the  acetylene  pressure-adjusting  screw  to  give  a 
slight  excess  of  Acetylene  to  the  flame. 

9.  Adjust  the  acetylene  needle  valve  to  give   a  neutral  flame 
(see  under  Flame  Regulation,  page  25) . 

How  to  Shut  Off  the  Blowpipe.  In  the  case  of  the  injector  type 
blowpipe,  first  close  the  acetylene  needle  valve,  and  then  the  oxygen 
needle  valve. 

In  the  case  of  pressure  blowpipes,  first  close  the  oxygen  needle 
valve,  and  then  the  acetylene  needle  valve. 

When  laying  aside  the  blowpipe  for  a  short  time,  the  pressure- 
adjusting  screws  on  both  regulators  should  be  released  by  turning  to 
the  left  until  free. 

When  work  is  suspended  for  any  considerable  time,  the  valves 
on  both  cylinders  should  be  closed. 


24  OXY-ACETYLENE  WELDING 

Never  light  the  blowpipe  unless  some  oxygen  is  passing  through  it. 
If  the  blowpipe  is  lighted,  or  burned,  with  only  acetylene  passing 
through  it,  there  will  be  a  deposit  of  carbon  made  in  the  tip,  which  will 
in  time  clog  the  orifice  and  interfere  with  the  perfect  operation  of 
the  blowpipe. 

Back=Firing.  If  the  flame  is  not  properly  adjusted,  or  the  tip 
becomes  clogged,  the  blowpipe  may  back-fire.  When  this  occurs, 
first  close  the  acetylene  needle  valve  quickly,  then  open  it  again  fully 
and  relight  the  blowpipe.  If  the  back-fire  continues,  close  both  the 
acetylene  and  oxygen  needle  valves.  Then  relight  the  blowpipe  and 
proceed  in  the  usual  manner. 

If  the  blowpipe  becomes  overheated,  it  may  back-fire.  When 
this  occurs,  it  may  be  cooled  by  plunging  it  into  a  bucket  of  water. 
Be  sure  that  the  acetylene  has  been  shut  off  and  a  small  quantity 
of  oxygen  is  flowing  through  the  blowpipe  to  prevent  water  backing 
into  the  tip  and  causing  further  back-firing  when  the  blowpipe  is 
relighted. 

Oxy-Acetylene  Blowpipe  Flame 

Character  of  Flame.  The  oxy-acetylene  flame  consists  of  two 
parts — an  inner  cone,  which  is  incandescent;  and  an  outer  envelope, 
or  nonluminous  flame,  which  is  sometimes  called  the  secondary  flame. 

The  temperature  of  the  oxy-acetylene  flame,  taken  at  the  extrem- 
ity of  the  inner  cone,  is  very  much  higher  than  that  of  all  other  flames. 
It  is  calculated  to  be  approximately  6300°  F.  One  of  the  main  reasons 
for  the  superiority  of  the  oxy-acetylene  flame  over  all  other  welding 
lies  in  the  fact  that  this  high  temperature  is  concentrated  at  the  point 
of  inner  cone. 

The  character  of  the  oxy-acetylene  flame  depends  upon  the 
proportion  of  oxygen  and  acetylene  contained  in  the  mixture  and 
the  thoroughness  of  the  mixture  as  it  issues  from  the  tip  of  the  blow- 
pipe. Varying  proportions  of  the  gases  produce  three  characteristic 
types  of  flame,  Fig.  18,  called,  respectively,  reducing,  or  carbonizing, 
flame ;  neutral,  or  welding,  flame ;  and  oxidizing  flame.  Each  type  has 
its  characteristic  appearance,  and  it  takes  only  a  little  practice  to 
instantly  recognize  each.  The  welder  should  at  all  times  observe 
carefully  the  type  of  flame  produced  and  promptly  correct  any 
divergence. 


OXY-ACETYLENE   WELDING  25 

Neutral,  or  Welding,  Flame.  A  neutral  flame  is  produced  when 
acetylene  and  oxygen  burn  in  the  proper  proportion,  theoretically 
1.00  volume  of  oxygen  to  1.00  volume  of  acetylene.  The  appearance 
of  this  flame  is  characteristic,  Fig.  18  b.  It  is  made  up  of  a  distinct 
and  clearly  defined  incandescent  cone,  or  jet,  of  bluish  hue,  surrounded 
by  a  faint  secondary  flame,  or  envelope,  purplish  yellow  in  color  and 
of  a  bushy  appearance. 

The  incandescent  cone  may  be  from  T£  to  f  inch  in  length  and  is 
usually  rounded  or  tapered  at  the  end.  The  maximum  temperature 
of  the  oxy-acetylene  flame  is  TG  to  ^  inch  beyond  the  extremity  of 
this  cone. 


Fig.  18.     Oxy-Acetylene  Flame.     Top,  Reducing  Flame;  Middle,  Neutral  Flame; 
Bottom,  Oxidizing  Flame 

The  middle  illustration  in  Fig.  18  shows  roughly  the  character- 
istic appearance  and  formation  of  the  neutral,  or  welding,  flame. 
This  flame  is  the  one  most  extensively  used,  and  no  welder  is  proficient 
until  he  is  thoroughly  familiar  with  its  appearance  and  distinguishing 
characteristics  and  is  able  to  maintain  this  flame  under  working 
conditions. 

Flame  Regulation.  The  neutral  flame  is  obtained  by  starting 
with  a  flame  having  a  slight  excess  of  acetylene  and  gradually  cutting 
down  the  acetylene  supply  by  means  of  the  blowpipe  needle  valve. 
As  this  is  done,  the  streaky  appearance  of  the  inner  cone  will 


26  OXY-ACETYLENE  WELDING 

gradually  diminish.  The  flame  is  neutral  when  the  streakiness  just 
disappears. 

Carbonizing,  or  Reducing,  Flame.  The  reducing,  or  carbonizing, 
flame  is  produced  when  there  is  an  excess  of  acetylene  in  the  flame. 
This  flame  is  of  an  abnormal  volume,  dirty  yellow  in  color,  of  uniform 
consistency,  and  has  a  streaky  appearance.  By  gradually  decreasing 
the  acetylene  supply  at  the  needle  valve,  the  size  of  the  flame  is 
decreased,  and  gradually  a  white  cone  of  great  luminosity  appears  at 
the  blowpipe  tip.  The  extent  .of  the  reducing,  or  carbonizing,  action 
of  the  flame  is  judged  practically  by  the  size  and  definition  of  the 
luminous  cone.  When  this  cone  becomes  more  clearly  defined  and 
takes  the  form  and  color  of  a  bluish  white  incandescent  cone,  or  pencil, 
the  streakiness  is  further  diminished,  and  the  flame  approaches  the 
neutral  stage.  The  upper  illustration  in  Fig.  18  shows  a  reducing,  or 
carbonizing,  flame  that  has  a  fair  but  not  large  excess  of  acetylene. 
The  temperature  of  the  reducing  flame  is  considerably  lower  than  that 
of  the  neutral  flame. 

Use  of  Reducing  Flame.  A  slight  excess  of  acetylene  is  used  in 
the  welding  of  brasses,  bronzes,  aluminum,  and  certain  alloy  steels 
to  guard  against  the  burning  out  of  easily  oxidized  elements.  It  has 
also  been  used  in  the  case  of  certain  mild  steels  to  increase  the  carbon 
content  to  secure  greater  hardness.  In  this  connection  it  must  be 
remembered  that  increase  in  hardness  is  usually  accompanied  by 
decrease  in  strength,  so  that  in  general  welding  an  excess  of  acetylene 
should  not  be  used. 

Oxidizing  Flame.  An  oxidizing  flame  is  produced  when  there  is 
an  excess  of  oxygen  in  the  flame.  The  effect  of  too  much  oxygen  is  to 
diminish  the  size  of  the  flame,  blunt  or  blurr  the  inner  cone,  and  pro- 
duce a  weak,  streaky,  or  scattering  flame.  In  some  blowpipes,  the 
inner  cone  is  not  only  diminished  in  size  but  is  slightly  bulged  at  its 
extremity  as  compared  with  the  neutral  flame,  which  is  shown  in 
the  middle  of  Fig.  18.  The  lower  illustration  in  Fig.  18  shows  the 
oxidizing  flame. 

Caution  Against  Oxidizing  Flame.  An  oxidizing  flame  should  be 
carefully  guarded  against  or  it  will  become  a  source  of  trouble.  An 
excess  of  oxygen  will  burn  the  metal,  causing  weak  welds,  and  in  the 
case  of  cast  iron  it  will  produce  a  hard  weld  that  will  be  difficult  to 
machine. 


OXY-ACETYLENE  WELDING 


27 


Manipulation  of  Blowpipe 
Position  of  Hose.  Occasionally 
operator's  shoulder.  In  this  case  the 
pended  and  held  by  the  hose  so  that  it 
peculiar  welding  motion  to  the 
blowpipe,  which  can  usually  be 
done  by  the  fingers.  However,  this 
method  is  not  generally  recom- 
mended, as  it  seriously  hinders  the 
free  movement  of  the  welding 
flame.  It  should  be  used  only  as 
a  relief  when  the  work  is  of  long 
duration  and  the  operator's  wrist 
and  forearm  become  tired. 

Position  of  Blowpipe.  The 
operator,  having  lighted  the  blow- 
pipe and  properly  adjusted  the 
flame,  is  now  ready  to  begin  weld- 
ing. Grasp  the  blowpipe  firmly 
in  the  hand,  as  shown  in  Fig.  19. 
The  blowpipe  is  so  designed  that  it 
balances  properly  when  grasped  at  this 
to  hold  the  blowpipe  in  the  fingers, 


and  Welding  Rod 

the  hose  is  thrown  over  the 
weight  of  the  blowpipe  is  sus- 
is  only  necessary  to  impart  the 


Fig.  19.     Correct  Method  of  Holding 
Welding  Blowpipe 


point.     It  is  not  good  practice 
because  it  is  not  possible  to 


Fig.  20.     Blowpipe  Should 
Not  Be  Inclined  Too  Much 


^.6.  -..     Blowpipe  Should 
Not  Be  Held  Too  Vertical 


Fig.  22.     Blowpipe  Should 
Not  Travel  Backwards 


manipulate  the  flame  with  as  great  regularity  and  control,  nor  will 
it  be  possible  to  do  as  heavy  work  without  tiring. 

Inclination  of  Blowpipe.     The  head  of  the  blowpipe  should  be 
inclined  at  an  angle  of  about  60  degrees  to  the  plane  of  the  weld. 


28  OXY-ACETYLENE  WELDING 

The  inclination  of  the  head  should  not  be  too  great,  Fig.  20,  because 
the  molten  metal  will  be  blown  ahead  of  the  welding  zone  and  will 
adhere  to  the  comparatively  cold  sides  of  the  weld.  On  the  other 
hand,  the  welding  head  should  not  be  inclined  too  near  the  vertical, 
Fig.  21,  or  the  secondary  flame  will  not  be  utilized  to  its  full  value  for 
pre-heating  the  metal  ahead  of  the  actual  welding. 

In  ordinary  welding  practice  it  is  best  that  the  top  of  the  blow- 
pipe be  so  inclined  and  so  directed  that  the  maximum  amount  of  pre- 
heating is  obtained  without  blowing  the  molten  metal  ahead. 

Travel  of  Blowpipe.  •  The  travel  of  the  blowpipe  should  be  away 
from  the  welder  and  not  toward  him,  Fig.  22,  as  the  work  can  be 
observed  more  closely  and  done  more  easily  and  quickly. 

Movement  of  Blowpipe.  In  making  a  weld  a  simultaneous  fusion 
of  the  edges  of  the  parts  to  be  joined  and  the  welding  rod  is  necessary. 
If  this  does  not  occur,  a  true  weld  is  not  produced. 


Fig.  23.     Circular  Motion  of  Blowpipe  for  Fig.  24.     Oscillating  Motion  of  Blowpipe 

Welding  Light  Sections  for  Welding  Heavy  Sections 

In  the  case  of  parts  which  have  been  chamfered  out  and  which 
require  the  use  of  filling  material,  a  peculiar  motion  must  be  imparted 
to  the  blowpipe,  which  will  take  in  both  edges  of  the  weld  and  the 
welding  rod  at  practically  the  same  time. 

In  comparatively  light  work  a  motion  is  imparted  to  the  blowpipe 
which  will  cause  the  incandescent  cone  to  describe  a  series  of  over- 
lapping circles,  as  shown  in  Fig.  23.  This  overlapping  extends  in  the 
direction  of  the  welding.  This  motion  must  be  constant  and  regular 
in  its  advance  so  that  the  finished  weld  will  have  a  good  appearance. 
The  speed  of  progress  should  be  such  that  complete  fusion  of  the  three 
members  referred  to  is  secured.  The  width  of  this  motion  is  depend- 
ent upon  the  size  of  the  material  being  welded  and  varies  accordingly 
with  the  nature  of  the  work.  It  does  not  take  much  experience  to 
establish  the  proper  size  motion  and  the  proper  rate  of  advance  for 
the  various  sizes  and  kinds  of  metals. 


OXY-ACETYLENE  WELDING 


29 


In  very  heavy  work,  if  the  above  system  were  used,  a  great  deal 
of  the  motion  would  be  superfluous.  Consequently,  a  movement 
in  which  the  cone  of  the  flame  will  describe  semi-circles  should  be  used, 
as  shown  in  Fig.  24.  This  confines  the  welding  zone  and  concentrates 
the  heat.  While  the  progress  is  not  so  fast,  it  is  more  thorough  than 
the  other  system  for  this  class  of  work. 

Importance  of  Movement.  To  the  average  beginner  the  regular 
control  from  these  motions  is  difficult.  It  requires  considerable 
practice  and  experience  to  become  skilled  in  this,  but  it  is  the  regu- 
larity of  these  motions  that  produces  the  characteristic  rippled  surface 
of  good  welding.  The  progress  of  a  welder  and  the  quality  of  his 
work  can  be  determined  to  some  extent  by  the  skill  with  which  he 
produces  this  effect. 

Position  of  Welding  Rod. 
After  the  beginner  has  mastered  the 
peculiar  motions  of  the  blowpipe, 
his  next  step  will  be  to  properly 
introduce  the  welding  rod  into  the 
weld  in  such  a  manner  that  the 
regular  advance  of  the  blowpipe 
will  not  be  hindered  or  retarded. 

The  welding  rod,  or  wire, 
should  be  held  and  inclined,  as 
shown  in  Fig.  25.  In  this  position  a  sufficient  quantity  of  material 
may  be  added  at  the  right  time.  If  the  welding  rod  were  held  in  a 
vertical  or  horizontal  position,  the  welder  would  be  liable  to  add  an 
excess  of  metal,  part  of  which  would  not  be  properly  fused. 

When  to  Add  Welding  Rod.  Great  care  must  be  taken  in  adding 
this  metal  that  the  edges  of  the  weld  are  in  their  proper  state  of  fusion 
to  receive  it.  If  the  metal  is  not  hot  enough,  the  added  material  will 
simply  adhere  to  the  sides,  resulting  in' adhesion  only,  not  a  true  weld. 
It  is,  therefore,  necessary  to  produce  equal  fusion  at  the  edges  of  the 
weld  with  that  of  the  welding  rod  by  the  correct  motion  of  the 
blowpipe. 

How  to  Add  Welding  Rod.  When  the  proper  time  arrives  to  add 
the  filling  material,  the  welding  rod  is  lowered  into  the  weld  until  it  is  in 
contact  with  the  molten  metal  of  the  edges.  When  in  this  position  the 
flame  of  the  blowpipe  is  directed  upon  it,  and  thus  fusion  is  produced. 


Fig.  25. 


Correct  Method  of  Holding 
Welding  Rod 


30  OXY-ACETYLENE  WELDING 

In  welds  of  unusual  depth  the  end  of  the  rod  is  immersed  in  the 
molten  metal  and  the  blowpipe  flame  is  played  around  it.  The 
material  is  thus  protected  from  the  air  and  the  gases  of  the  blowpipe. 
The  heat  of  fusion  in  this  case  is  supplied  mostly  from  the  molten 
metal  which  surrounds  the  rod. 

Faults  to  Be  Avoided.  The  usual  faults  of  the  average  beginner 
are  :  first,  failure  to  introduce  the  welding  rod  into  the  welding  zone 

at  the  proper  time;  second,  to  hold 
the  rod  at  the  wrong  angle;  and 
third,  to  fuse  either  too  little  or 
too  much  of  the  rod.  The  filling 
material  when  melted  should  never 
be  allowed  to  fall  into  the  weld  in 
drops,  or  globules,  Fig.  26. 

Building  Up  the  Weld.  In 
welding  it  is  customary  to  build  up 
the  welded  portion  in  excess  of  the 


AiFk-J?6;   ^e,1,di-nf  Rov  s^¥  Not  Be        thickness  of  the  original  section. 

Allowed  to  Fall  into  the  Weld  in  Drops 

There  are  several  reasons  for  doing 

this.  First,  the  weld  is  reinforced  and  the  strength  is  accordingly 
increased.  Second,  in  case  it  is  desired  to  finish  the  surface  there  is 
sufficient  stock  to  allow  machining.  Third,  in  some  cases  small  pin- 
holes  or  blowholes  may  be  found  just  under  the  surface  of  a  weld, 
which  do  not  extend  to  any  depth  in  the  weld  and  may  be  removed 
by  filing  or  machining. 

GENERAL  NOTES  ON  WELDING 

The  above  are  basic  principles  involved  in  producing  all  good 
oxy-acetylene  welds.  There  are  many  detailed  operations  which 
must  be  learned  by  practice  for  the  successful  handling  of  the 
different  metals,  but  by  keeping  in  mind  these  basic  principles  and 
by  applying  them  properly,  the  more  difficult  operations  can  be  readily 
mastered. 

Haste  Fatal  to  Good  Welding.  It  is  a  fundamental  rule  for 
successful  welding  that  the  operator  must  give  his  undivided  attention 
to  the  work  in  hand.  Do  not  try  to  hurry  over  or  slight  any  step  of  the 
work.  You  cannot  weld  faster  than  the  metal  will  melt  and  fuse 
together. 


OXY-ACETYLENE  WELDING 


31 


Fig.  27.     Method  of  Filling  in  a  Deep 
Hole— Start  at  the  Upper  Edge 


Burning  a  Hole  in  the  Metal.    Occasionally  an  operator  becomes 
so  interested  in  some  minor  detail  of  his  work  that  he  allows  the  flame 
to  burn  through  the  metal  and  form 
a  hole. 

How  to  Weld  Up  a  Hole.  It  is 
a  difficult  operation  for  a  beginner 
to  fill  these  holes.  His  first  at- 
tempts usually  result  in  enlarging 
the  holes  instead  of  closing  them. 
The  proper  way  to  take  care  of 
this  is  to  incline  the  blowpipe  so 
that  the  flame  is  almost  parallel  to 
the  surface  of  the  work,  Fig.  27. 
With  the  blowpipe  in  this  position, 
play  the  flame  upon  the  upper  edge  of  the  hole  until  the  sides  become 
plastic,  taking  care  that  the  edges  do  not  become  entirely  fused. 
When  the  edge  is  in  the  proper  condition,  the  welding  rod  is  interposed 
and  a  small  amount  of  metal  is  added  to  the  top  edge  of  the  hole. 
This  operation  is  repeated  until  the  hole  is  filled  in.  As  the  work  pro- 
gresses, the  blowpipe  is  gradually  raised  until  it  resumes  its  normal 
position. 

Overhead  and  Vertical  Welding.  In  welding  overhead,  Fig.  28, 
or  vertically,  Fig.  29,  the  same 
procedure  is  followed  as  in  filling  a 
hole.  The  metal  should  not  be 
allowed  to  reach  the  state  of  fusion 
that  is  secured  in  ordinary  weld- 
ing. It  should  be  hot  enough  to 
assimilate  the  welding  rod,  but  not 
so  fluid  that  it  will  flow  out  of  the 
weld.  In  overhead  welding  care 
should  be  taken  that  oxidation 
does  not  occur,  because  the 
molten  oxide  will  flow  from  the 
weld  and  seriously  inconvenience  Fig.  28.  Overhead  Welding 

the  operator. 

Beginning  a  Long  Weld.     In  beginning  a  long  weld  pains  should 
be  taken  to  see  that  it  is  started  properly,  and  at  this  point  of  the 


32 


OXY-ACETYLENE  WELDING 


work  time  should  not  be  spared.     When  the  weld  is  properly  started 
the  speed  may  be  increased.     As  the  weld  advances  the  speed  becomes 


Fig.  29.     Vertical  Welding 

greater,  because  the  material  becomes  heated  up  and  the  blowpipe 
action  is  faster. 

Defects  in  Welds.  There  are  a  number  of  sources  of  defects 
in  welds,  and  the  average  beginner  usually  encounters  all  of  them 
before  he  becomes  a  skilled  welder. 

Improper  Flame  Adjustment.  If  the  flame  is  not  properly 
adjusted  the  weld  will  be  inferior.  The  commonest  fault  is  the 
presence  of  too  much  oxygen  in  the  welding  flame.  Unless  the 
operator  takes  a  great  deal  of  care  in  removing  the  oxidized  particles, 
they  will  be  incorporated  in  the  weld,  Fig.  30.  The  oxide,  of  course, 


Fig.  30.     Oxidized  Weld 


Fig.  31.     Failure  to  Completely  Penetrate  to  the 
Bottom  of  the  Weld 

greatly  decreases  the  strength  and  greatly  affects  the  other  mechanical 
properties  of  the  weld. 


OXY-ACETYLENE  WELDING 


33 


Adhesion  of  Added  Metal  to  Edges  of 
the  Weld 


Failure  to  Penetrate.  A  fault,  not  only  of  the  beginner  but  also  of 
the  skilled  operator,  is  failure  to  penetrate  to  the  bottom  of  the  weld, 
Fig.  31,  and  is  the  cause  of  a  great  many  defective  welds.  In  his 
desire  to  complete  a  weld  as  soon  as  possible,  the  operator  very  often 
hastens  over  the  most  important 
part  of  the  work,  which  is  to 
secure  the  absolute  fusion  of  the 
edges  at  the  bottom  of  the  weld. 
Failure  to  do  this  not  only  Fig.  32. 
reduces  the  section  of  the  metal 
at  the  weld,  but  also  gives  a  line  of  weakness  in  case  the  welded 
pieces  are  submitted  to  bending  or  transverse  strains. 

Adhesion  of  Added  Metal.  When  molten  metal  from  the  welding 
rod  is  added  to  the  edges  of  the  weld  which  are  not  in  fusion,  a  weld 
is  not  secured.  The  added  metal  merely  adheres  to  the  cooler  metal, 
Fig.  32,  and  perfect  fusion  is  not  secured.  Adhesion  may  be  caused 
by  improperly  chamfering  the  pieces  to  be  welded,  by  improper  incli- 
nation of  the  blowpipe,  by  improper  use  of  the  welding  rod,  or  by 
faulty  regulation  and  manipulation  of  the  welding  flame. 

The  tendency  of  beginners  is  to  not  prepare  the  pieces  properly 
for  welding.  Usually  the  chamfering,  or  grooving,  is  either  not  deep 
enough,  that  is,  does  not  extend  entirely  through  the  section  to  be 
welded,  or  it  is  not  wide  enough.  In  welding  pieces  improperly 
prepared  the  tendency  of  adhesion  is  great. 

The  most  common  fault  is  the  addition  of  the  welding  rod  to  the 
edges  of  the  weld  before  they  are  in  fusion.  The  adhesion  in  this  case 
is  applied  to  both  edges.  Sometimes  one  edge  of  the  weld  is  in  fusion, 
but  the  other  is  not.  In  this  case  adhesion  is  applied  to  only  one  side, 


Fig.  33.     Weld  Not  Properly  Reinforced  Fig.  34.     Weld  Properly  Reinforced 

but  with  the  effect  that  the  strength  of  the  weld  is  lessened  the  same 
as  when  adhesion  occurs  on  both  sides. 

In  some  cases  the  edges  of  the  metal  are  brought  to  a  state  of 
fusion  too  soon,  so  that  oxide  has  an  opportunity  to  form  on  the  edges 


34  OXY-ACETYLENE  WELDING 

of  the  weld.  Then,  when  the  welding  rod  is  added,  adhesion  occurs 
with  a  film  of  oxide  separating  the  edges  and  the  added  material. 

Often  an  operator  will  concentrate  the  flame  upon  the  welding 
rod  and  the  edges  of  the  weld.  Then,  as  the  blowpipe  is  played 
around  the  welding  rod,  some  of  the  molten  metal  is  forced  ahead. 
The  metal  ahead  is  not  in  the  proper  state  of  fusion  and  consequently 
adhesion  results. 

Insufficient  Reinforcing.  It  is  not  uncommon  to  see  welds 
produced  that  do  not  contain  enough  metal,  Fig.  33.  All  welds 
should  be  reinforced  with  additional  metal  as  in  Fig.  34.  In  case  a 
smooth  finish  is  desired  this  excess  metal  can  be  removed  by  grinding 
or  machining.  Too  great  an  excess  of  metal  must  not  be  added  be- 
cause this  takes  extra  time  and  the  gases  are  wasted. 

WELDING  FOR  DIFFERENT  METALS 
PROPERTIES  OF  METALS 

Before  the  beginner  takes  up  the  actual  welding  of  metals,  it  is 
necessary  that  he  study  their  properties,  peculiarities,  and  behavior 
under  the  action  of  the  welding  flame.  Some  of  the  physical  proper- 
ties of  the  more  common  metals  are  given  in  Table  I. 
.  Melting  Point.  The  first  property  that  the  welder  should 
consider  is  the  melting  point  or  temperature  at  which  the  metal  will 
fuse  or  become  fluid.  The  average  welder  is  usually  fairly  familiar 
with  the  difference  in  melting  points  of  lead  or  zinc,  and  iron  or  steel ; 
but  he  is  usually  not  familiar  with  the  difference  between  the  melting 
points  of  brass,  bronze,  copper,  white  cast  iron,  gray  cast  iron,  etc. 
This  knowledge  is  especially  important  if  it  becomes  necessary  to  weld 
members  of  dissimilar  materials. 

Thermal  Conductivity.  The  conductivity  of  a  metal  is  its 
ability  to  transmit  heat  throughout  its  mass.  This  property,  which 
is  not  the  same  for  all  metals  and  varies  within  wide  limits,  is  of  great 
importance  to  the  welder.  It  can  be  seen  that  if  one  metal  conducts 
or  transmits  the  heat  from  the  welding  blowpipe  more  rapidly  through- 
out its  mass  than  another,  it  is  necessary  that  allowance  be  made  both 
as  to  the  pre-heating  equipment  and  the  size  of  the  blowpipe  used. 

In  welding  metals  of  high  thermal  conductivity,  it  is  necessary 
to  use  oversize  blowpipes — as  in  the  case  of  copper.  Although  the 


OXY-ACETYLENE  WELDING 


35 


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36  OXY-ACETYLENE  WELDING 

melting  point  of  copper  is  low,  yet  the  conductivity  is  high,  and, 
consequently,  a  blowpipe  of  the  same  size  as  would  be  used  on  a 
similar  section  of  steel  must  be  used. 

The  conductivity  of  a  metal  will  have  a  great  bearing  on  the 
consideration  of  expansion  and  contraction.  If  one  metal  absorbs 
or  leads  the  heat  away  from  the  welding  blowpipe  more  rapidly  than 
another,  the  heated  area  will  become  very  much  larger,  and,  conse- 
quently, the  expansion  and  contraction  more  severe. 

Specific  Heat.  The  specific  heat  of  a  metal  is  the  amount  of 
heat  that  is  absorbed  when  it  is  raised  through  a  certain  range  of 
temperature.  A  metal  having  a  low  melting  point  but  relatively 
high  specific  heat  may  require  as  much  heat  to  bring  it  to  its  point  of 
fusion  as  a  metal  of  high  melting  point  and  low  specific  heat —  as  in 
the  case  of  aluminum  compared  to  steel. 

Coefficient  of  Expansion.  The  linear  increase  per  unit  length 
when  the  temperature  of  a  body  is  raised  through  one  degree  is  its 
coefficient  of  expansion. 

The  coefficient  of  expansion  varies  materially  with  the  different 
metals.  Of  the  metals  most  commonly  welded,  as  seen  from  Table  I, 
aluminum  has  the  greatest  expansion,  bronze  and  brass  next,  then 
copper,  steel,  and  iron.  Aluminum  expands  almost  twice  as  much 
as  iron  or  steel,  consequently,  in  dealing  with  aluminum  work  it  is 
necessary  that  this  feature  be  considered  very  seriously. 

Expansion  and  Contraction.  When  a  body  of  any  material  is 
subjected  to  an  increase  in  temperature,  it  expands  and  its  volume 
and  linear  dimensions  are  increased.  When  the  temperature  is 
lowered  a  reverse  action  takes  place,  the  body  contracts,  and  its 
volume  and  linear  dimensions  decrease.  Metals  or  metallic  bodies 
are  very  susceptible  to  this  change  in  volume  due  to  variations  in 
temperature. 

The  effect  of  this  expansion  and  contraction  is  of  great  impor- 
tance to  the  welder.  It  is  impossible  for  the  welder  to  produce  satis- 
factory work  until  he  has  a  knowledge  of  the  nature  and  the  amount 
of  expansion  usually  encountered  and  of  how  to  compensate  for  it. 

The  expansion  and  contraction  of  the  welded  piece  cannot 
be  controlled  or  arrested  mechanically,  because  the  force  of  expansion 
is  irresistible.  In  malleable,  or  ductile,  metals  the  expansion  is  liable 
to  produce  warping  or  deformation  of  the  piece,  while  in  materials 


OXY-ACETYLENE  WELDING 


37 


that  are  not  of  this  nature — brittle  materials — such  as  cast-iron,  the 
result  of  the  expansion  and  contraction,  unless  properly  taken  care  of, 
is  fracture. 

If  the  expansion  can  take  place  in  all  directions,  it  will  give  the 
welder  no  trouble,  as  the  piece  will  expand  equally  all  over,  and  upon 
cooling  will  contract  to  its  original  volume.  If,  however,  the  welding 
takes  place  at  a  point  that  is  confined  by  various  parts  or  by  the  par- 
ticular construction  of  the  piece,  it  is  then  necessary  to  give  it  due 
consideration. 

The  resultant  effect  of  contraction,  produced  by  the  cooling  of 
the  welded  object,  must  be  considered  equally  with  that  of  expansion. 
Contraction  produces  as  much  cracking,  or  checking,  and  warping  as 
does  expansion.  Therefore,  it  is  essential  that  the  welder  study  not 
only  the  effect  of  expansion,  but  also  the  subsequent  result  produced 
.by  contraction. 

Methods  of  Handling  Expan- 
sion and  Contraction.  There  are 
many  ways  of  taking  care  of 
expansion  and  contraction,  such 
as  heating  the  entire  piece  to  a 
dull  red  heat,  simultaneously 
heating  opposing  similar  parts, 
and  breaking  the  piece  at  certain 
points  to  allow  free  expansion  and  then  re-welding  at  the  break.  If  the 
material  is  ductile  or  malleable,  it  may  be  warped  or  bent  out  of 
shape  to  such  an  extent  that  the  spring  will  take  up  completely  the 
opposing  force  of  expansion  and  contraction.  This,  however,  entails 
an  accurate  calculation  and  should  not  be  used  except  where  no  other 
means  are  feasible. 

Handling  Simple  Case  of  Expansion  and  Contraction.  We  will 
first  consider  the  simplest  condition  of  welding.  Assume  that  a  long 
bar  which  is  free  at  each  end  has  broken  at  point  A,  Fig.  35.  In  this 
case  the  welding  may  be  carried  out  without  any  fear  of  encountering 
difficulties  due  to  expansion  and  contraction.  The  bar  is  free  to 
expand  and  contract  at  each  end.  While  there  might  be  some  warp- 
ing or  deformation  due  to  the  heat  of  welding  if  the  blowpipe  is  not 
handled  properly,  yet,  there  is  very  little  danger  of  weakening  the 
weld  because  of  internal  strains. 


Fig.  35.     Simple  Case  of  Expansion  and 
Contraction 


38  OXY-ACETYLENE  WELDING 

Now  let  us  assume  that  this  bar  is  part  of  a  casting,  as  shown  at  C, 
which  is  surrounded  and  joined  to  a  rigid  frame  B  and  D.  In  this 
case  the  expansion  and  contraction  due  to  welding  must  be  taken 
care  of.  It  is  readily  seen  that  the  expansion  is  not  the  force  that  will 
cause  trouble,  because  when  the  two  pieces  expand  during  welding, 
the  metal,  which  is  in  a  fused  condition,  is  so  soft  that  the  expansion 
can  take  place  in  the  weld  and  the  edges  will  approach  each  other. 
This  will  not  affect.the  confined  frame.  However,  consider  the  action 
on  the  metal  when  it  starts  to  cool.  Contraction  sets  in  and,  as  it  is 
irresistible,  there  must  be  some  compensation  for  the  shortening  of 
the  bar  C.  If  the  material  is  ductile  and  one  that  will  stand  bending, 
deformation  or  warping  will  occur.  But,  if  it  is  of  low  ductility,  such 
as  cast  iron,  a  break  will  occur  either  at  the  weld  or  at  a  line  of  less 
resistance. 

Methods  of  Handling.  In  welding  an  article  of  the  general 
nature,  shown  in  Fig.  35,  when  the  break  is  in  an  internal  member, 
such  as  at  C,  there  are  several  ways  of  handling  it. 

Heating  Entire  Casting.  The  entire  piece  can  be  raised  to  a  high 
temperature  as  referred  to  above  and  in  this  way  produce  an  expan- 
sion in  the  entire  mass,  and,  consequently,  equal  contraction.  How- 
ever, this  is  not  necessary,  and  in  some  cases  is  not  possible;  the 
operation  also  takes  more  time  and  costs  more.  It  is  only  necessary 
at  the  time  of  welding  to  heat  simultaneously  similar  parts  to  a  good 
red  heat,  in  order  that  the  stiffness  of  the  frame  may  be  lessened,  and 
thus  take  care  of  the  contraction. 

Heating  Confining  Members.  In  the  example  referred  to,  the 
application  of  a  pre-heating  burner  at  the  points  B  and  D  will  cause 
the  frame  to  expand  in  the  linear  direction  of  the  expansion  and  con- 
traction produced  by  the  weld.  Therefore,  when  the  weld  is  finished 
and  the  frame  starts  to  cool  and  contract,  the  parts  B  and  C,  in  as 
much  as  they  were  raised  to  practically  the  same  temperature  as  the 
metal  surrounding  the  weld,  will  contract  equally  and,  therefore,  a 
successful  weld  will  be  produced. 

Use  of  Wedges.  If  it  is  impossible  to  apply  pre-heating  at  the 
points  referred  to,  another  method  may  be  used.  By  the  use  of 
jacks,  wedges,  or  similar  devices,  a  casting  such  as  shown  in  Fig.  35 
may  be  sprung  or  bent  out  of  shape,  and  the  edges  of  the  part  to 
be  welded  may  be  separated.  After  the  weld  is  executed  and  con- 


OXY-ACETYLENE  WELDING 


39 


traction  sets  in,  the  jacks,  wedges,  etc.,  may  be  withdrawn.  The  return 
of  the  sprung  parts  to  their  original  positions  will  compensate  the 
contracting  strains. 

Breaking  Another  Member.  Another  method  of  taking  care  of 
expansion  and  contraction  is  that  of  breaking  the  piece  at  some  extra- 
neous point,  such  as  at  E.  In  this  case  the  expansion  and  contraction 
will  be  free  to  act  at  the  point  C  without  any  fear  of  serious  after- 
effect, as  the  casting  is  free  to  spring  in  any  direction,  because  of  the 
loose  joint  at  E.  As  the  point  E  is  not  confined,  it  is  an  easy  matter 


Fig.  36.     Complex  Case  of  Expansion  and  Contraction 

to  reweld  this  break  without  fear  of  any  bad  results.  This  method, 
however,  is  dependent  upon  the  thickness  of  the  metal  and  is  one 
that  should  not  be  attempted  unless  no  other  means  are  feasible. 

While  this  diagram  is  extremely  simple,  nevertheless  the  prin- 
ciples to  be  considered  and  the  methods  of  handling  them  are  indenti- 
cal  with  those  experienced  in  all  practical  work.  A  clear  conception 
of  the  forces  acting,  the  nature  of  their  action,  and  how  to  counteract 
them,  is  essential  in  work  with  the  oxy-acetylene  blowpipe. 

Handling  Complex  Case  of  Expansion  and  Contraction.  A  good 
example  of  a  complex  case  of  expansion  and  contraction  is  the  fly- 
wheel or  pulley  with  broken  spokes,  as  shown  in  Fig.  36. 


40  OXY-ACETYLENE  WELDING 

Assume  that  the  spoke  is  broken  at  A.  If  this  were  welded  with- 
out considering  and  allowing  for  expansion  and  contraction,  the 
shrinkage  strain  would  be  so  great  that  failure  would  occur. 

Pre-heating  the  rim  from  W  to  X  to  a  dull  red  heat  will  cause  the 
rim  to  expand  outwardly,  separating  the  edges  of  the  broken  spoke. 
While  in  this  state  the  weld  should  be  made  rapidly  and  then  the 
entire  wheel  allowed  to  cool  slowly.  Thus  a  good  weld  without  the 
presence  of  internal  strains  will  be  produced.  The  expansion  of  the 
rim,  due  to  the  pre-heating,  will  offset  the  contraction  of  the  weld 
in  the  spoke. 

If  the  crack  in  the  spoke  is  near  the  rim,  it  is  only  necessary  to 
apply  a  gas  or  oil  burner  to  the  rim  at  M  until  it  is  at  a  red  heat. 
This  will  expand  the  spoke  and  rim,  and  separate  the  edges  of  the 
break  sufficiently  to  offset  the  contraction  of  the  weld. 

The  spoke  may  be  welded  at  A  without  pre-heating  if  the  confin- 
ing member — in  this  case  the  rim — is  broken  to  lessen  the  rigidity. 
In  order  to  do  this  the  rim  must  be  broken  at  a  point  P,  always  close 
to  the  spoke.  First  one  side  of  the  spoke  is  strongly  tacked  at  the 
weld.  Then  the  other  side  is  welded  two-thirds  the  way  through. 
The  tack  is  then  melted  out  and  the  weld  completed.  The  rim  is  then 
welded  at  point  P.  If  the  edges  do  not  meet  accurately,  they  may  be 
brought  to  do  so  by  heating  either  at  M  or  0,  according  to  which  edge 
is  low. 

If  two  spokes  are  broken  as  at  A  and  B,  the  same  general  pro- 
cedure as  given  above  may  be  followed.  In  case  it  is  necessary  to 
pre-heat  a  large  portion  of  the  casting  it  is  important  that  the  pre- 
heated area  always  extend  beyond  the  spokes  adjacent  to  those 
fractured,  from  Y  to  Z. 

If  two  diametrically  opposite  spokes  are  broken  such  as  B  and  C, 
each  may  be  treated  as  independent  of  the  other  and  welded  by  any 
of  the  methods  given  above. 

PRE-HEATING 

Reasons  for  Pre=H  eating.  Pre-heating  is  employed  for  three 
fundamental  reasons: 

To  Compensate  for  Expansion  and  Contraction.  When  pre-heat- 
ing is  used  to  counteract  the  effects  of  expansion  and  contraction,  it 
is  necessary  that  the  casting  be  heated  either  in  certain  confined 


OXY-ACETYLENE  WELDING  41 

localities  or  entirely  to  a  dull  red,  or  in  some  cases  to  a  bright  red  heat. 
With  this  treatment  the  internal  strains  existing  in  all  welds  are 
reduced  to  a  minimum. 

To  Decrease  Cost  of  Welding.  When  a  weld  is  being  executed 
on  a  large  casting,  it  is  too  expensive  to  supply  the  total  amount 
of  heat  required  from  the  blowpipe  alone.  To  offset  this,  pre-heating 
by  some  cheaper  method  is  used,  and  the  result  is  usually  a  saving 
of  from  25  to  60  per  cent  of  the  cost  of  welding  by  means  of  the  blow- 
pipe alone.  Then,  too,  it  is  possible  to  accomplish  the  welding  with 
greater  speed,  due  to  the  casting  being  at  a  higher  temperature. 

To  Make  Metal  More  Receptive  to  Action  of  Welding  Flame.  When 
the  temperature  of  a  metallic  body  is  raised,  the  state  of  the  metal 


Fig.  37.    Pre-Heating  with  Welding  Blowpipe  Fig.  38.     Gas  Burner  for  Pre-Heating 

surrounding  the  weld  is  more  nearly  that  of  the  molten  metal  in  the 
weld,  and  the  result  is  a  more  homogeneous  and  smoother-grained 
union,  dependent  upon  the  temperature  reached  in  pre-heating. 

Methods  of  Pre=Heating.  There  are  various  means  of  carrying 
out  this  preliminary  heating.  The  method  used  should  be  governed 
by  the  particular  work  in  hand. 

Pre-  Heating  with  Welding  Blowpipe.  The  simplest  method  and 
the  one  most  used  on  light  objects  is  that  of  utilizing  the  flame  of  the 
welding  blowpipe,  Fig.  37.  In  welding  thin  castings,  it  is  only 
necessary  that  the  flame  of  the  blowpipe  be  played  upon  the  parts  at 
the  line  of  the  weld  for  a  few  moments,  in  order  that  the  pieces  may 
obtain  a  red  heat.  This  is,  however,  expensive,  and  should  only  be 
employed  on  small  objects. 


42 


OXY-ACETYLENE   WELDING 


Gas  and  Oil  Burners.     If  the  article  to  be  welded  is  of  fairly  large 
size,  the  use  of  gas,  Fig.  38,  or  oil  burners,  Fig.  39,  is  economical. 


Fig.  39.     Oil  Burner  for  Pre-Heating 
Courtesy  of  Oxweld  Acetylene  Company,  Chicago,  Illinois 


Fig.  40.     Charcoal  Fire  for  Pre-Heating  Castings 

These  pre-heating  torches,  however,  limit  the  area  of  the  surface 
covered,  so  consequently  are  used  more  successfully  on  that  work 


OXY-ACETYLENE  WELDING  43 

which  requires  localized  pre-heating.  The  flames  produced  are  of 
sufficient  temperature,  but  not  the  necessary  volume  to  evenly  heat 
the  entire  casting. 

Charcoal  Fire.  The  most  satisfactory  method  of  pre-heating  is 
by  means  of  a  charcoal  fire  built  around  the  article  to  be  welded. 
The  usual  procedure  is  to  build  a  small  temporary  fire-brick  furnace 
around  the  piece  and  fill  in  with  charcoal,  Fig.  40.  This  is  ignited  by 
means  of  kerosene.  As  the  progress  of  the  ignition  of  the  charcoal 
is  rather  slow,  the  pre-heating  is  carried  out  gradually.  The  nature  of 
this  pre-heating  flame  is  of  such  evenness  and  volume  that  the  tem- 
perature imparted  to  the  casting  is  the  same  throughout  its  mass. 

In  welding  large  castings  of  a  complicated  nature,  such  as  engine 
cylinders,  it  is  necessary  that  they  be  pre-heated  evenly  throughout 
and  that  the  welding  be  carried  on  while  the  casting  is  at  a  dull  red 
heat.  Therefore,  the  most  satisfactory  means  of  accomplishing  this 
is  by  embedding  the  casting  in  charcoal  and  carrying  on  the  work 
while  it  is  embedded  in  the  hot  coals. 

STEEL  WELDING 

General  Considerations.  The  welding  of  steel  is  apparently 
simple,  but  in  reality  it  is  a  fairly  difficult  material  to  weld  and 
should  receive  the  welder's  best  thought  and  care.  It  is  simple  to 
produce  a  nice  looking  weld  that  has  a  smooth  even  surface,  but  it  is 
not  easy  to  produce  a  weld  that  is  strong  and  will  stand  up  under 
service.  Welds  of  high  strength  are  absolutely  necessary  in  cases  like 
automobile  frame  and  crankshaft  repairs,  because  a  poor  weak  weld 
might  prove  fatal. 

Oxidation.  It  is  practically  impossible  to  prevent  a  certain 
amount  of  oxidation;  but  it  is  very  important  that  it  be  kept  to  a  mini- 
mum. The  oxide  that  forms  on  the  top  of  the  weld  may  be  removed 
quite  easily,  because  it  melts  at  a  lower  temperature  than  the  metal. 
It  may  be  floated  off  the  weld  while  hot,  or  removed  as  a  thin  skin 
after  the  weld  becomes  cold.  Care  must  be  taken,  when  adding  the 
welding  rod,  Fig.  30,  page  32,  that  this  film  of  oxide  is  penetrated, 
because  if  this  is  not  done  the  oxide  will  be  incorporated  in  the  weld, 
which  will  therefore  be  very  weak. 

Expansion  and  Contraction.  The  effect  of  expansion  and  con- 
traction is  not  as  severe  in  steel  welding  as  in  cast  iron  or  aluminum; 


44  OXY-ACETYLENE  WELDING 

but,  nevertheless,  it  must  receive  due  consideration.  In  steel  castings 
it  is  taken  care  of  in  a  manner  similar  to  that  used  for  cast  iron,  that 
is,  by  pre-heating.  In  sheet-steel  work  the  creeping,  or  drawing,  of 
the  edges  is  taken  care  of  by  arranging  the  edges  of  the  sheets  at  an 
angle,  or  by  tacking,  or  by  the  use  of  jigs  to  hold  the  work. 

Welding  Rod.  Each  welding  head  is  designed  for  use  with  a 
certain  thickness  of  metal.  As  the  volume  of  the  flame  varies  with 
the  size  of  the  welding  head,  care  must  be  used  to  select  a  welding 
rod  of  the  correct  size  in  making  welds  in  sheets  of  various  thickness. 
There  is  great  danger  of  burning  a  welding  rod  that  is  too  small,  or, 
if  the  rod  is  too  large,  it  may  not  melt  through  and  will  enter  into  the 
weld  in  a  semifused  condition  and  not  be  thoroughly  incorporated  in 
the  weld.  The  following  table  shows  the  proper  size  of  welding  rod 
to  be  used  for  the  different  thicknesses  of  sheets: 

THICKNESS  OF  SHEET  SIZE  OF  WELDING  ROD 

Up  to  J  inch  TQ  inch 

I  to  A  inch  J  inch 

J  to    f  inch  A  inch 

|  inch  and  over  J  inch 

Never  use  twisted  wire  made  up  of  two  or  more  strands,  because 
this  offers  a  very  large  surface  for  oxidation,  which  is  a  condition 
operators  must  try  to  avoid. 

Neutral  Flame.  The  importance  of  maintaining  a  neutral  flame 
at  all  times  cannot  be  emphasized  too  strongly.  An  excess  of  acety- 
lene in  the  flame  tends  to  carbonize  the  work,  resulting  in  a  hard 
brittle  weld;  while  an  excess  of  oxygen  will  oxidize  or  burn  the  metal. 
It  is  seldom  necessary  to  adjust  the  flow  of  gases  through  the  blowpipe 
after  correct  adjustment  has  once  been  made,  except  in  the  case  of 
very  heavy  welding  where  the  intense  heat  of  the  molten  metal  tends 
to  expand  the  orifice  in  the  tip  of  the  welding  head.  This  has  some 
effect  on  the  size  and  shape  of  the  flame  and  necessitates  more  or  less 
frequent  adjustment  to  keep  the  gases  in  correct  proportion  to  main- 
tain the  neutral  flame. 

Movement  of  Blowpipe  and  Addition  of  Welding  Rod.  In  welding 
sheet  steel,  it  is  necessary  that  the  oscillating  movement  previously 
referred  to  be  imparted  to  the  blowpipe  and  used  continuously— 
both  because  of  its  high-melting  point  and  the  behavior  of  the  molten 
metal  under  the  action  of  the  blowpipe  flame.  Steel  cannot  be  pud- 


OXY-ACETYLENE  WELDING  45 

died  and  it  is  therefore  necessary  to  add  the  filling  material  in  thin 
overlapping  layers.  The  importance  of  securing  a  perfect  bond 
between  every  two  layers  can  be  readily  seen.  To  make  a  true  weld, 
a  simultaneous  fusion  of  the  edges  of  the  sheets  and  the  welding  rod 
must  be  produced. 

To  do  this  with  light-  and  medium-weight  sheets,  a  motion  is 
imparted  to  the  blowpipe  which  will  cause  the  flame  to  describe  a 
series  of  overlapping  circles  as  previously  described,  page  28.  This 
overlapping  extends  in  the  direction  of  the  welding  and,  in  order  to 
make  a  weld  of  good  appearance,  must  be  constant  and  regular  in 
its  advance. 

In  heavier  plates,  while  the  same  rule  governing  simultaneous 
fusing  of  the  edges  of  the  sheets  and  welding  rod  apply,  the  filling  of 
the  groove  is  accomplished  in  a  slightly  different  manner.  On 
account  of  the  depth  of  the  weld  the  flame  is  not  large  enough  to 
fuse  a  body  of  metal  of  so  great  an  area,  and  it  is  impossible  to  fill  the 
groove  entirely  from  bottom  to  top  with  one  layer  of  metal.  The 
bottom  edges  of  the  groove  must  first  be  thoroughly  fused  for  an  inch 
or  two  before  adding  metal.  When  this  is  done,  bring  the  flame  back 
to  the  starting  point  and  when  the  metal  is  in  the  proper  molten 
condition  add  the  filling  material,  oscillating  the  blowpipe  in  a  series 
of  semicircles,  as  previously  recommended  for  welding  heavy  sections, 
page  29.  Follow  this  method  of  filling  the  groove  in  sectional  layers 
until  the  proper  height  is  reached,  making  sure  that  thorough  fusion 
is  accomplished  between  the  layers  themselves  and  the  edges  of  the 
sheet  and  the  layers  of  filling  material. 

After- Treatment.  Correct  after-treatment  is  as  essential  for 
successful  welding  of  steel  as  the  actual  welding  operation.  Proper 
after-treatment  will  improve  the  grain  of  the  metal  and  will  materially 
increase  the  strength  and  toughness  of  the  weld.  There  are  three 
principal  treatments  that  will  benefit  the  material  and  are  easily 
employed  in  the  repair  shop.  These  are  called  annealing,  hammering, 
and  quenching. 

Annealing.  Annealing  consists  of  reheating  the  work  to  the 
proper  temperature  and  then  allowing  it  to  cool  slowly.  The  work 
should  be  heated  to  a  bright  cherry  red  by  means  of  a  blowpipe  or 
suitable  burner,  or  in  a  furnace  that  can  be  carefully  regulated.  Care 
must  be  taken  that  the  work  reaches  the  bright  cherry  red,  because 


46 


OXY-ACETYLENE  WELDING 


heating  to  a  lower  temperature  will  be  detrimental  and  may  leave  the 
weld  weaker  than  if  not  annealed  at  all.  After  the  work  has  been 
heated,  it  should  be  allowed  to  cool  very  slowly  and  evenly.  It 
should  be  covered  over  with  asbestos  or  dry  sand,  packed  in  lime,  or 
left  to  cool  in  the  furnace.  Care  must  be  taken  that  cold  air  currents 
do  not  strike  the  work  before  it  has  become  cold. 

Hammering.  Hammering  consists  of  reheating  the  weld  to 
the  proper  temperature  and  then  hammering  while  at  this  tempera- 
ture with  a  hand  hammer.  The  weld  should  be  heated  to  a  bright 
yellow  heat  and  then  hammered  with  quick  light  blows.  Heavy 
hammers  or  heavy  blows  should  never  be  used.  The  hammering 
should  cease  as  soon  as  the  weld  falls  to  a  dull  red,  for  otherwise 
the  fine  grain  of  the  metal  will  be  spoiled  and  the  weld  will  be  weak. 

Quenching.  Quenching  consists  of  reheating  the  work  to  the 
proper  temperature  and  then  plunging  it  into  water,  brine,  or  oil. 
This  method  is  used  mainly  for  small  articles.  It  is  used  quite  often 
for  hardening  and  tempering.  Quenching  should  be  employed  only  in 
special  cases,  because,  although  it  will  make  the  work  strong,  it  will 
also  make  it  hard  and  brittle. 

Light  Sheet-Steel  Welding 

Preparation.  In  welding  two  short  pieces  of  flat  steel,  up  to  A 
inch  in  thickness,  no  special  preparation  of  the  plates  is  necessary, 

except  to  have  them  flat  as  possible 
and  to  be  sure  that  the  edges  are 
reasonably  true.  The  two  pieces  of 
metal  should  be  placed  on  a  level 
surface,  preferably  fire  brick  or 
some  other  nonconductor  of  heat. 
Expansion  and  Contraction. 
With  light  sheet,  expansion  and 
contraction  are  cared  for  by  tacking 
the  seam  at  certain  intervals  or  by 
arranging  the  sheets  so  that  the 
edges  to  be  welded  are  set  at  a 
slight  angle  rather  than  parallel, 


Fig.  41.     Light  Sheets  in  Position  for 
Welding 


Fig.  41.    The  correct  amount  of  divergence  is  determined  by  the 
thickness  of  the  metal  and  should  be  from  2J  to  6  per  cent  of  the 


OXY-ACETYLENE  WELDING 


47 


length  of  the  weld.  The  amount  of  divergence  between  these  limits 
varies  also  with  the  speed  of  welding,  fast  welding  requiring  less 
spread.  After  the  plates  are  in  this  position,  place  two  pieces  of  flat 
bar  steel  on  each  side,  about  \  inch  from,  and  parallel  to,  the  line  of 
the  weld.  Clamp  or  weight  these  pieces  down  so  that  they  cannot 
be  readily  moved.  The  work  is  now  in  position  for  welding. 

Jigs.  In  making  this  type  of  weld  in  flat  sheet  steel  in  longer 
lengths,  up  to  several  feet  and  up  to  ^  inch  in  thickness,  a  welding 
jig  made  up  with  two  slotted  jaws  hinged  at  one  end  and  provided 
with  hold-down  clamps  at  the  other  end  will  be  found  more  conven- 
ient than  the  individual  hold-down  bars. 


Fig.  42.     Jig  for  Holding  Light  Sheet  Cylinders  for  Welding 

For  welding  short  cylinders,  a  jig  made  similar  to  that  shown  in 
Fig.  42  will  be  found  satisfactory. 

Tacking.  Tacks,  or  short  welds,  at  intervals  of  from  2  to  6 
inches,  according  to  the  thickness  of  the  sheet,  can  be  made  the  entire 
length  of  the  seam  to  hold  the  edges  in  position  for  welding  if  jigs 
are  not  available. 

One  of  the  above  methods  must  be  used  to  take  care  of  the 
creeping  action  due  to  expansion  when  the  flame  of  the  blowpipe 
is  applied  to  the  metal.  If  this  action  is  not  provided  against  and 
the  two  sheets  are  placed  with  parallel  edges,  they  will  first  diverge 


48 


OXY-ACETYLENE  WELDING 


when  the  welding  is  started,  as  in  a,  Fig.  43,  and  then  gradually  come 
together.  When  about  half  of  the  weld  has  been  made,  they  will  again 
become  parallel  as  in  b.  From  this  point  on  as  the  welding  continues 
the  sheets  will  draw  together  until  they  overlap,  as  shown  in  c. 


(a) 


Fig.  43.     Result  of  Not  Providing  for  Expansion 


Welding  Light  Sheet.  Select  the  welding  head  and  a  piece  of  iron 
welding  rod  of  the  size  suitable  for  the  thickness  of  the  sheet  and 
place  the  work  in  position  for  welding. 

As  steel  is  very  sensitive  to  the  action  of  the  carbonizing 
flame  and  particularly  to  that  of  the  oxidizing  flame,  a  constant, 
nonvarying,  neutral  flame  should  be  maintained.  The  incandescent 
jet  should  be  of  maximum  size  and  clear  outline  at  all  times. 

With  the  correct  neutral  flame,  start  welding  at  the  point 
where  the  two  sheets  meet.  Impart  the  circular  motion  to  the 
blowpipe,  described  under  Movement  of  Blowpipe,  page  28,  to 
produce  the  correct  rippled  surface  on  the  finished  weld.  When  the 


Fig.  44. 


Appearance  of  Good  Weld  in  Light 
Sheet  Steel 


Fig.  45. 


Appearance  of  Poor  Weld  in  Light 
Sheet  Steel 


weld  is  finished,  turn  out  the  blowpipe  and  allow  the  work  to  cool 
until  the  metal  is  black. 

Then  remove  the  hold-down  bars  and  examine  the  weld.  It 
you  have  followed  instructions,  your  weld  will  have  the  appearance 
shown  in  Fig.  44  and  will  not  be  like  that  shown  in  Fig.  45.  On 


OXY-ACETYLENE  WELDING 


49 


Fig.  46.     Lai 
Should  Never  : 


Welds 
tellsed 


Fig.  47.     Butt  Weld  in 
Light  Sheet 


closer  examination  you  will  find  that  all  the  particles  of  dirt  and 

impurities  you  noticed  floating  on  the  top  of  the  molten  metal  when 

you  were  welding  are  now  lying  with  the  oxide 

on  top  and  alongside  of  the  weld  where  they  can 

be  readily  brushed  or  scraped  off.      Now  take 

your  job  to  the  shears  and  cut  off  one  or  two 

pieces.     Upon  examination,   the  cross-section  should  present  the 

same  uniform  texture  and  color  in  both  the  weld  and  the  sheet. 

Types  of  Welds  in  Light  Sheet.     Lap  Weld.    Lap  joints,  either 
single  or  double,  Fig.  46,  should  never  be  used 
in  welding  sheets   of   any  thickness  because 
the  weld  will  be  subjected  to  a  shearing  strain. 

Welds  should  be  under  tension  or  compres- 
sion strains,  never  under  shearing  or  bending  strains. 

Butt  Weld.    The  most  common  and  the  simplest  weld  to  prepare 
in  light  sheet  is  the  butt  joint,  shown  in  Fig.  47. 

Flange  Weld.    Another  type  of  weld  in  light* 
sheet,  but  one  that  entails  some  preparation,  is  Fig- 
made  by  flanging  up  the  welding  edges  about  ^ 
to  YQ  inch,  Fig.  48,  laying  the  two  pieces  flat  and  parallel  on  the  weld- 
ing table  and  executing  a  flange,  or 
edge,  weld.    It  is  not  necessary  to 
use  welding  wire  with  this  type  of 
weld,  because   the  metal   in  the 
flanges  when    they  are  fused  to- 
gether acts  as  a  filling  agent.     By 
careful  manipulation  the  edges  can 
be  fused  down  to  a  small  bead, 
practically  flush  with  the  surface 
of  the  sheet. 

Cylinders.  In  welding  light 
sheets  that  have  been  rolled  in 
cylindrical  form,  the  separation  of 
the  edges  can  be  accomplished  by 
placing  a  wedge  about  two-thirds 


Fig.  49.     Method  of  Welding  Light  Sheet 
Cylinders — Using  Wedge  to  Space  the  Edges 


of  the  way  down  the  length  of  the  seam  after  the  welding  is  started, 
Fig.  49.  As  the  welding  progresses  the  wedge  should  be  moved  further 
along  the  seam  and  withdrawn  entirely  as  the  work  nears  completion. 


50 


OXY-ACETYLENE   WELDING 


Tacking  can  also  be  resorted  to  in  welding  cylindrical  forms, 
although  this  results  in  the  deformation  of  the  cylinder,  as  shown 

in  Fig.  50,  and  makes  it  necessary 
to  hammer  or  re-roll  the  cylinder 
into  shape. 

The  edges  of  very  light  sheet 
cylinders  can  be  flanged  and  an 
edge,  or  flange  weld,  executed;  but 
this  method  cannot  be  recom- 
mended with  sheets  heavier  than 
TS  inch. 

Corner  Welds.  In  making  a 
corner  weld  in  the  lighter  gage 
sheets  up  to  A  inch,  the  edges  of 
the  sheet  should  be  flanged,  as 
shown  in  Fig.  51.  In  sheets  from 
i^  to  A  inches  in  thickness,  it  is 
only  necessary  that  the  edges  of 


Fig.  50.     Result  of  Tacking  a  Light  Sheet 
Cylinder — The^Weld  Draws  up  Pointed 


the  sheets  run  as  true  as  possible  in  position,  as  shown  in  Fig.  52. 
Tacking  is  necessary  in  this  case,  as  the  sheets,  due  to  expansion, 


r~ 

Fig.  51.     Corner  Weld 

for  Very  Light  Sheets, 

up  to  A  Inch  Thick 


Fig.  52.     Corner  Weld 

for  Light  Sheets,    &  to 

A  Inch  Thick 


g.  53.     Sharp  Corner 
feld  for  Light  Sheets 


readily  move  out  of  position  when  welding  is  commenced.   On  welds 
of  this  latter  type  it  is  necessary  to  use  welding  wire. 

Two  other  forms  of  corner 
welds  are  illustrated  in  Figs.  53 
and  54.  These  sheets  should  be 
tacked  and,  if  YS  incn  or  thicker, 
welding  wire  should  be  used. 
Tank  Heads.  In  making 
tanks  when  either  a  bottom  or  heads  in  both  ends  are  required,  the 
method  of  putting  in  the  heads  is  governed  by  the  design  and  pur- 
pose for  which  the  tank  is  intended. 


Fig.  54.     Broad  Corner  Weld  for 
Light  Sheets 


OXY-ACETYLENE  WELDING 


51 


Storage  Tanks.  If  the  tank  is  to  be  used  as  a  storage  receptacle, 
such  as  gasoline  tanks,  the  heads  can  be  cut  to  the  outside  diameter 
of  the  shell,  laid  flat  on  the  end  of  the  shell  and  tacked  at  intervals 
all  the  way  around,  Fig.  55.  Then  the  shell,  with  the  heads  securely 
tacked  in  place,  is  laid  on  its  side  and  the  welding  is  started  at  any 
point,  the  tank  being  turned,  from  time  to  time,  as  the  welding 
progresses.  Or,  the  heads  can  be  flanged  to  any  depth  desired, 
and  backed  into  the  shell  until  the  edge  of  the  flange  and  the  edge  of 
the  shell  are  even,  Fig.  56,  making  sure  that  the  head  fits  the  shell 
snugly.  They  are  then  tacked  and  welded  in  an  upright  position. 
This  latter  method  is  the  better  of  the  two  from  the  welding  stand- 
point. 

Pressure  Tanks.  When  a  tank  is  built  to  stand  a  considerable 
pressure,  such  as  air-compressor  tanks,  the  heads  should  always  be 
dished  and  flanged,  the  boiler-maker's  standard  specifications  govern 


Fig.  55.     Head  Weld 
for  Storage  Tanks 


Fig.  56.     Head  Weld  for 
Storage  and  Medium- 
Pressure  Tanks 


Fig.  57.     Head  Weld 
for  Pressure  Tanks 


this.  The  heads  can  be  either  backed  in  and  an  edge  weld  made, 
Fig.  56,  or  set  up  so  that  the  edges  of  the  flange  exactly  meet  the 
edges  of  the  shell,  Fig.  57.  In  either  case  the  parts  should  be  tacked 
together  before  welding.  In  the  second  case,  care  should  be  used 
in  flanging  to  have  the  outside  diameter  of  the  flange  exactly  the 
same  as  the  outside  diameter  of  the  shell.  This  method  is  the  best 
because  the  weld  is  under  direct  tension  or  straight  pull. 

Tubes.  Light-weight  tubing  should  be  squared  off  and  fitted 
nicely  before  welding  is  attempted.  It  should  be  tacked  in  several 
places  and  then  welded. 

Heavy   Sheet-Steel  Welding 

Preparation.  In  welding  heavy  sheet  metal  above  TS  inch  in 
thickness,  a  certain  amount  of  preparation  is  necessary.  The 
success  of  the  weld  depends  in  a  great  measure  upon  the  proper 


52 


OXY-ACETYLENE  WELDING 


preparation  of  the  work  to  be  welded.  While  the  preparation  is 
governed  largely  by  the  particular  location  of  the  weld  and  form 
of  the  sheets  to  be  welded,  there  are  certain  general  rules  that  must 

always  be  observed. 

In  making  a  perfect 
weld  it  is  necessary  that 
the  metal  at  the  weld 
be  completely  fused 
throughout  its  entire 
thickness.  In  light  sheets 
the  projection  of  the 
flame  is  great  enough  to 
produce  this  result,  but  heavy  sheets  would  require  a  flame  of  such 
magnitude  that  it  could  not  be  readily  handled.  Therefore,  in  order 
to  facilitate  complete  fusion,  the  edges  of  the  sheets  to  be  welded  are 


Fig.  58.     Heavy  Sheets  in  Position  for  Welding 


Fig.  59.     Welding  Heavy  Plate  Steel  Cylinder 
Note  grooving  of  edges,  spacing  clamps  and  wedge  about  half  way  along  the  seam 

chamfered  or  beveled  to  form  a  V-groove,  the  width  of  this  V  being 
equivalent,  or  nearly  so,  to  the  thickness  of  the  metal. 


OXY-ACETYLENE  WELDING  53 

Expansion  and  Contraction.  With  heavy  sheet,  expansion  and 
contraction  are  cared  for  by  observing  the  same  rules  of  spacing, 
Fig.  58,  and  clamping,  Fig.  59,  or,  in  some  cases,  tacking,  in  order 
to  hold  the  work  in  position  for  welding,  as  described  for  light 
sheets  on  page  47. 

Welding  Heavy  Sheet.  Select  a  welding  head  and  a  piece  of 
iron  welding  rod  of  the  proper  size  to  accomplish  the  work  in  hand. 

Because  steel  is  sensitive  to  the  carbonizing  and  oxidizing  flames, 
it  is  necessary  to  maintain  the  correct  oxygen  pressure  and  a  neutral 
flame  at  all  times.  In  ordinary  heavy  sheet  welding  there  are  two 
general  methods  of  procedure,  either  of  which  will  produce  a  good 
weld  when  properly  executed.  These  methods  may  be  called  weld- 
ing by  sections,  and  continuous  welding. 

Welding  by  Sections.  Welding  is  started  by  first  playing  the 
flame  of  the  blowpipe  along  the  edges  of  the  pieces  to  be  welded. 
This  is  done  merely  as  a  preliminary  heat  treatment.  The  flame 
is  then  played  on  the  bottom  of  the  groove  at  the  beginning  of  the 
weld  until  the  edges  are  in  a  molten  condition,  at  which  time  the 
blowpipe  is  momentarily  withdrawn  and  the  molten  metal  allowed 
to  flow  together.  This  is  done  without  the  aid  of  any  filling  material. 
Care  must  be  exercised  at  this  point,  because  successful  welding 
depends  upon  complete  penetration  and  perfect  union  of  the  bottom 
edges.  When  a  perfect  union  of  the  two  members  is  secured  for 
about  one  or  two  inches,  the  welding  rod  is  brought  into  use.  By 
playing  the  flame  around  the  welding  rod  in  contact  with  the  edges 
of  the  weld  instead  of  directly  on  the  welding  rod,  it  is  possible 
to  bring  them  both  to  the  point  of  fusion  simultaneously.  The  rod 
is  then  gradually  added  to  the  weld,  layer  by  layer,  until  this  par- 
ticular section  of  the  weld  is  built  up  to  the  required  height.  The 
flame  is  then  played  on  the  face  of  the  metal  just  added  and  on  the 
bottom  of  the  groove  until  fusion  of  these  parts  is  secured.  The 
welder  then  repeats  the  operation  described  above  until  the  next 
small  section  of  the  groove  is  filled  up  to  the  proper  level.  The 
welding  progresses  by  means  of  these  small  sections,  each  being  built 
up  completely  before  another  is  started. 

While  the  metal  is  in  a  fused  condition,  the  velocity  of  the  flame 
will  cause  the  molten  metal  to  become  slightly  indented.  The 
flame  should  be  withdrawn  momentarily,  from  time  to  time,  thus 


54  OXY-ACETYLENE  WELDING 

allowing  the  fluid  metal  to  flow  back  to  its  normal  level,  in  which 
position  it  will  solidify.  Skill  in  steel  welding  depends  greatly  on 
this  manipulation,  as  the  flowing  together  of  the  different  molten 
centers  produces  the  weld. 

Continuous  Welding.  In  this  method  the  weld  advances  con- 
tinuously with  each  addition  of  metal.  By  this  method  the  metal 
is  added  in  short  layers,  sloping  rather  than  horizontal.  The  weld 
is  started  by  fusing  together  the  bottom  edges  of  the  groove  as  pre- 
viously described.  The  filling  material  is  then  added  so  that  it 
will  be  from  f  to  J  inch  high  at  the  starting  point  and  slope  to  nothing 
in  a  length  of  1  or  1J  inches  along  the  bottom  of  the  groove.  This 
will  give  an  inclined  surface  to  which  the  filling  material  is  added 
in  parallel  layers.  The  added  metal  being  on  a  sloping  plane,  the 
fusion  of  the  bottom  edges  is  always  carried  ahead  with  the  welding, 
as  each  layer  includes  a  small  section  of  the  bottom  of  the  groove. 

Types  of  Welds  in  Heavy  Sheet.  Lap  Weld.  As  explained  on 
page  49,  the  lap  weld  should  never  be  used. 

Butt  Weld.  The  beveled  or  grooved  butt  joint  is  the  only 
welded  joint  that  should  be  employed  on  heavy  sheets,  Fig.  60. 

The  most  satisfactory  method  of 

edges,    because    tacking   is    very 

Fig.  60.     Butt  Weld  in  Heavy  Sheets  ,.,     ,  ,111          i  i 

likely  to  not  hold  on  heavy  sheets. 

Never  weld  sheets  from  both  sides,  because  unequal  strains 
are  likely  to  be  introduced  by  localized  heating  when  working  on 
the  second  side. 

Cylinders.  Heavy  cylinders  should  also  be  prepared  for  the 
grooved  butt  weld,  for  the  same  reasons  as  for  heavy  sheets. 


Fig.  61.     Corner  Welds  for  Heavy  Sheets 

Corner  Welds.    The  two  most  satisfactory  corner  welds  for 
heavy  sheet  are  shown  in  Fig.  61.    Although  the  second  is  a  little 


OXY-ACETYLENE  WELDING 


55 


more  costly  to  prepare,  it  is  more  satisfactory  than  the  first  because 
it  insures  better  penetration. 

Tank  Heads.  In  welding  bottoms  or  heads  in  tanks  of  heavy 
sheet,  the  purpose  for  which  the  tank  is  to  be  used  governs  the  method 
of  constructing  the  heads  as  it  does  in  welding  tanks  of  lighter  gage. 
The  same  general  rules  apply  in  both  cases,  the  main  difference  being 


C 

Fig.  62.     Head  Weld  for 
Storage  Tanks 


Fig.  63.     Head  Weld  for 
Medium-Pressure  Tanks 


Fig.  64.     Head  Weld  for 
High-Pressure  Tanks 


that  the  edges  of  the  heavy  shells  and  heads  are  chamfered,  de- 
pendent on  the  design  of  the  tank.  All  require  tacking  to  hold  the 
members  in  position  for  welding. 

Storage  Tanks.  In  the  case  of  putting  on  a  flat  head,  the  edge 
of  the  head  only  is  chamfered,  Fig.  62,  while  in  putting  in  a  flanged 
head  where  an  edge  weld  is  to  be  executed,  as  in  Fig.  63,  both  shell 
and  head  are  chamfered  to  make  the  V-groove. 


P    LJ 


Fig.  65.     Welds  for  Tank  Reinforcing  Rings 

High-Pressure  Tanks.  When  a  head  is  put  in,  as  shown  in 
Fig.  64,  both  the  edge  of  the  flange  and  the  edge  of  the  shell  are 
chamfered.  This  type  of  head  is  the  best  for  high-pressure  tanks 
because  the  weld  is  in  tension. 

This  method  also  applies  to  the  welding  of  two  cylindrical 
shells  end  to  end  in  making  tanks  of  such  dimensions  that  one 
single  sheet  of  steel  is  not  large  enough  to  make  a  complete  shell. 


56 


OXY-ACETYLENE  WELDING 


Tank  Rings.    In  welding  angle-iron  rings  to  tanks  of  the  same 
thickness,  it  is  necessary  that  the  edges  of  both  ring  and  shell  be 


Fig.  66.     Various  Pipe  Joint  Welds 

beveled  as  at  the  left,  Fig.  65.  Two  methods  of  welding  heavy 
rings  to  lighter  shells  are  shown  at  the  middle  and  right.  The  inside 
weld  at  the  right  should  be  only  enough  to  smooth  off  the  joint. 

n«BAMBB      If   too  much  heat  is  applied  from  the 
inside  there  is  likely  to  be  trouble  from 
warping  or  buckling.  Rings  should  always 
u    ,__  m~- — ^vJ      be  tacked  to  prevent  bowing,  twisting  of 

Fig.  67.     Welds  for  Pipe  Heads          tne  rings>  an(J  buckling  of  the  shell. 

Tubes  and  Pipes.  Various  tube  and  pipe  welds  are  given  in 
Fig.  66. 

The  methods  for  closing  the  end  of  a  pipe  with  a  head  are 
shown  in  Fig.  67.  The  first  is  the  easier  and  stronger  of  the  two. 

ILD.  £L 

Fig.  68.     Welds  for  Pipe  Flanges 

Three  methods  of  welding  flanges  to  pipe  are  shown  in  Fig.  68. 
Hie  first  method  is  easier  to  weld  than  the  second;  but  the  latter 


OXY-ACETYLENE  WELDING 


57 


Fig.  69.    Preparation  of  Heavy  Forgings  for 
Welding 


is  the  stronger.      The  third  method  is  the  best  method  of  welding 
flanges  to  pipe,  but  is,  of  course,  a  special  type  of  flange. 

Welding  Heavy  Steel  Forgings  and  Steel  Castings 

Preparation.     In  welding  heavy  steel  sections,  such  as  crank- 
shafts, axles,  and  the  like,  the  weld  is  prepared  by  grooving  or  beveling 
from  both  sides.     This  is  done 
because  it  is  easier  for  the  oper- 
ator to  do  the  work  and  for  the 
sake  of  economy,  because  by 
beveling  from  both  sides  less 
filling  material  is  necessary  and, 
consequently,  less  time  and  gas 
are  needed. 

Square  Sections.     Square   or  rectangular  sections  of  forgings 
are  best  prepared  by  beveling  half  way  through  from  each  side, 
Fig.  69.    After  the  welding  has 
been  carried  on  from  one  side, 
the  piece  turned  over  and  the 
welding    completed    from 
the    second    side,    there    will 
probably  be  a  slight  bow,  or 
curve.    In  the  case  of  forgings,          Fig.  70. 
this  is  not  objectionable,  be- 
cause the  work  can  be,  and,  in  fact,  should  be,  reheated  and  straight- 
ened.   The  reheating  in  the  case  of  forgings  is  beneficial  to  the  grain 
of    the    material    and    the 
strength  of  the  weld.      With 
castings,  however,  this  bend- 
ing is  not  possible.    There- 
fore,  to  keep  the   work  in 
alignment,  it  is  best  to  pre- 
pare the  work  as  shown  in  Fig.  70.    The  welding  is  carried  on  two- 
thirds  of  the   way  through  from  the  first  side,  and  then  finished 
by  turning  over  and  working  from  the  second  side. 

Round  Sections.  Round  or  elliptical  sections  should  be  prepared 
by  beveling  the  ends  to  a  wedge  as  indicated  in  Fig.  71.  They  should 
never  be  turned  down  to  a  point.  By  preparing  the  pieces  as  shown 


Preparation  of  Heavy  Castings  for 
Welding 


Fig.  71.    Preparation  of  Round  Sections  for  Welding 


58 


OXY-ACETYLENE  WELDING 


in  the  illustration,  the  welder  will  have  a  flat  surface  to  build  his 
weld  upon.  If  the  work  were  prepared  to  a  point,  the  filling  material 
when  added  would  have  no  surface  to  lie  upon  and  would  run  down 
in  drops,  necessitating  burning  or  melting  away  when  the  work 
is  turned  over,  and  probably  resulting  in  a  weak  weld  with  con- 
siderable oxide. 

Expansion  and  Contraction.  Expansion  and  contraction  will 
probably  cause  very  little  trouble  to  the  operator  in  the  case  of 
shafts  and  other  heavy  pieces  that  are  not  connected.  The  only 
difficulty  the  operator  will  encounter  in  these  cases  will  be  the  possible 
bending,  which  was  noted  above,  when  welding  from  two  sides. 
However,  if  the  broken  part  is  confined  by  rigid  members,  the  work 
should  be  handled  either  by  pre-heating,  or  one  of.  the  other  methods 

recommended  and  ex- 
plained under  Expan- 
sion and  Contraction, 
pages  36  to  40. 

V-Blocks.  When 
welding  shafts,  it  is  ad- 
visable to  line  them  up  in 
position  on  V-blocks,  so 
that  they  may  be  turned 
over  and  still  kept  in 
Fig.  72.  "V  Blocks  for  Welding  shaft.  alignment,  Fig.  72. 

Welding  Heavy  Section.  In  the  case  of  a  heavy  section  select 
the  proper  size  welding  head  and  a  piece  of  welding  rod  of  the  cor- 
rect analysis  for  the  particular  work  at  hand,  and  place  the  work  in 
alignment.  , 

If  the  section  is  over  or  about  one  inch,  it  should  be  pre-heated 
by  means  of  a  gas  or  oil  burner  until  it  is  at  a  red  heat.  This  will 
save  oxygen  and  acetylene,  and  will  bring  the  material  to  a  tempera- 
ture at  which  it  will  be  more  receptive  to  the  action  of  the  welding 
flame  and  thereby  insure  a  more  homogeneous  weld.  If  not  objec- 
tionable to  the  operator,  it  is  advisable  to  let  the  pre-heating  burner 
play  on  the  work  while  the  welding  operation  is  going  on,  taking 
care,  of  course,  that  the  materials  of  combustion  of  the  pre-heating 
burner  do  not  strike  the  molten  metal  and  have  a  detrimental  effect 
on  the  weld. 


OXY-ACETYLENE   WELDING  59 

The  welding  flame  is  first  played  on  the  edges  at  the  bottom  of 
the  groove  until  they  are  in  a  molten  condition.  The  flame  is  then 
momentarily  withdrawn  to  allow  them  to  flow  together  and  "set", 
and  form  the  bottom  of  the  weld.  When  a  perfect  union  of  the  bottom 
is  secured  all  the  way  across,  the  welding  rod  is  brought  into  use. 
By  playing  the  flame  around  the  welding  rod  and  the  edges  of  the 
weld  instead  of  directly  on  the  welding  rod,  it  is  possible  to  bring 
them  to  a  fusing  temperature  at  the  same  time.  The  rod  is  then 
gradually  added  to  the  weld,  layer  by  layer,  until  the  entire  groove 
has  been  filled  up.  The  welding  rod  is  kept  plunged  into  the  molten 
metal  all  the  time  to  prevent  oxidation.  Any  oxide  that  forms  during 
the  welding  is  floated  to  the  top  and  removed  by  scraping  with  the 
welding  rod,  or  by  blowing  away  with  the  force  of  the  welding  flame. 
The  welder  must  be  careful  that  he  does  not  allow  the  molten  metal 
to  run  over  the  sides  of  the  weld.  Each  layer  is  added  in  such  a 
way  that  it  extends  slightly  beyond  the  end  of  the  groove.  Then, 
from  time  to  time,  as  the  groove  is  filled  up,  the  operator  smooths 
down  the  two  ends. 

Hammering.  As  each  section,  about  \  inch  thick,  is  added 
to  the  groove,  the  operator  stops  the  welding  operation,  heats  the 
work  to  a  bright  yellow,  and  hammers  the  weld  lightly  but  rapidly 
to  give  it  as  fine  a  grain  as  possible.  After  the  weld  has  been  com- 
pleted, it  is  either  hammered  or  annealed,  as  directed  on  page  45. 

CAST-IRON  WELDING 

General  Considerations.  Many  defects  are  experienced  by  the 
beginner  in  welding  cast  iron  because  of  its  peculiar  properties.  The 
two  principal  faults  noticed  are  the  production  of  hard,  glassy,  and 
brittle  metal  in  the  weld,  and  subsequent  cracks,  breaks,  and  checks 
either  in  the  weld  or  in  the  adjacent  metal,  owing  to  excessive  internal 
strains  set  up  by  unequal  contraction.  Both  are  serious  defects,  and 
the  liability  of  their  occurrence  is  so  great  that  proper  preventive 
methods  should  be  continually  borne  in  mind  and  applied  while 
welding  this  material. 

Oxidation.  Cast  iron  melts  at  about  2000°  to  2190°  F.,  and 
iron  oxide  melts  at  about  2450°  F.  The  oxide  is  formed,  however, 
at  low  temperatures,  a  bright  red  heat  being  sufficient  to  cause 
the  combination  of  oxygen  from  the  air  with  the  iron  of  the  casting. 


60  OXY-ACETYLENE  WELDING 

It  is  not  possible  to  melt  this  oxide  and  flow  it  from  the  weld,  so  it 
remains  in  the  casting  in  the  form  of  thin  flakes  or  crust.  This 
not  only  prevents  the  alloying  of  the  molten  metal,  but  also  combines 
with  the  free  carbon  and  is,  consequently,  conducive  to  the  formation 
of  white  iron.  Therefore,  this  oxide  must  be  removed  or  destroyed. 

Expansion  and  Contraction.  Cast  iron  is  absolutely  lacking  in 
elasticity,  and  its  tensile  strength  is  very  low.  In  preparing  work 
for  welding,  it  is  always  necessary  to  take  fullest  precautions  against 
the  bad  effects  of  expansion  and  contraction.  Expansion  and  con- 
traction should  be  treated  with  more  importance  in  the  welding  of 
cast  iron  than  in  any  other  metal. 

When  the  internal  strain  produced  by  contraction  is  greater 
than  the  tensile  strength  of  the  section  to  which  it  is  confined,  fail- 
ure will  occur.  When  the  strain  is  not  great,  but  still  exists,  the 
resistance  of  the  section  to  external  stresses  is  reduced  in  proportion. 
Thus  a  casting  may  appear  to  be  normal  after  welding  but  the 
excessive  internal  strains  caused  by  the  welding  may  make  it  fail 
at  the  slightest  shock. 

One  of  the  three  general  methods  of  coping  with  the  forces  of 
expansion  and  contraction,  which  are  given  on  pages  36  to  40, 
must  be  used  when  welding  cast  iron.  The  proper  method  to  pursue 
is  determined  by  the  size  and  shape  of  the  casting  and  the  nature 
and  location  of  the  break.  A  very  large  percentage  of  the  failures 
due  to  shrinkage  cracks  may  be  prevented  by  an  intelligent  anticipa- 
tion of  the  forces  of  expansion  and  contraction  and  the  proper  hand- 
ling of  the  work  to  overcome  these. 

Pre=Heating.  Pre-heating  should  be  used  to  some  extent  in 
all  cast-iron  welding.  If  the  piece  is  small  and  the  break  is  so  located 
that  it  is  not  necessary  to  consider  expansion  and  contraction,  the 
blowpipe  should  be  played  upon  it  until  the  chill  is  removed  from 
the  casting.  If  the  casting  is  large,  an  oil  or  gas  burner,  or  charcoal 
fire  can  be  used.  In  a  large  casting  this  preliminary  heat  treatment 
not  only  favors  the  execution  of  a  good  weld  but  also  requires  less 
oxygen  and  acetylene  because  of  this  large  volume  of  heat  from  a 
cheap  source,  thereby  reducing  the  cost  of  welding. 

Welding  Rods.  The  success  of  cast-iron  welding  depends 
greatly  upon  the  selection  of  a  suitable  welding  rod.  It  has  been 
proved  time  and  again  that  hard,  brittle,  and  weak  welds  have  been 


OXY-ACETYLENE   WELDING  61 

produced  for  no  other  reason  than  because  inferior  filling  material 
was  used. 

The  presence  of  silicon  in  proper  proportion  tends  to  produce 
a  soft  gray-iron  weld.  It  increases  the  fluidity  of  the  metal,  retards 
oxidation,  and  prevents  decarbonization  and  blowholes.  The 
success  of  the  filling  rod  is  dependent  upon  the  amount  of  this  ele- 
,  ment  it  contains.  From  3  to  4  per  cent  is  the  average  silicon  content 
of  good  welding  rods.  The  welding  rod  must  be  of  high-grade  cast 
iron,  soundly  cast  and  absolutely  homogeneous.  It  must  be  free  from 
all  sand,  grit,  and  rust.  For  convenience  in  handling,  it  is  usually 
cast  in  24-inch  lengths  of  three  diameters,  J,  f,  and  |  inch.  In 
case  either  a  longer  or  heavier  rod  is  desired,  two  or  more  are  welded 
together. 

Flux.  The  principal  problem  that  confronts  the  welder  is  to 
prevent  the  formation  of  oxide,  and  in  case  it  is  formed,  to  reduce 
it  and  remove  it  from  the  weld.  If  this  is  not  done,  the  molten 
metal  will  be  enclosed  in  a  thin  film  of  nonmetallic  material,  and 
any  additional  metal  that  may  be  fused  or  added  will  adhere  to  this 
film  rather  than  break  through  it  and  fuse  homogeneously  with  the 
other  metal.  It  is  not  possible  to  satisfactorily  break  up  this  film 
mechanically,  therefore  it  must  be  reduced  to  a  molten,  or  slag, 
condition.  To  accomplish  this  a  suitable  flux  is  used  that  will  dissolve 
the  oxide. 

A  flux  is  not  used  solely  to  dissolve  the  oxide,  but  also  to  float 
off  other  impurities,  such  as  sand,  scale,  and  dirt.  It  forms  a 
protecting  glaze  on  the  weld  and  surrounding  surfaces  and  increases 
the  fluidity  of  the  molten  metal. 

Borax  and  salt  (sodium  chloride)  are  two  compounds  often 
used  by  welders,  but  they  really  contain  little  merit  as  a  flux.  Their 
low  fusibility  seems  to  be  the  only  point  in  favor  of  their  use. 
Occasionally,  they  may  be  employed  to  advantage  in  welding  heavy 
sections  or  burned  iron,  such  as  are  found  in  firebox  and  grate  cast- 
ings, but  their  function  is  only  that  of  a  cleanser.  Both  tend  to 
produce  hard  iron.  There  are  certain  flux  powders  put  on  the  market 
that  contain  large  proportions  of  manganese.  These  powders  cannot 
help  but  have  a  hardening  effect  on  the  iron.  Others  contain  potas- 
sium perchlorate,  a  violent  oxidizing  agent.  Still  others  contain 
material  that  chlorinize  the  weld.  Needless  to  say,  powders  of  this 


62  OXY-ACETYLENE  WELDING 

kind  must  not  be  used.  It  is  best  to  guard  against  the  purchase  of 
such  defective  mixtures  by  obtaining  flux  powders  from  reliable 
sources. 

It  is  necessary  that  the  welder  learn  to  apply  flux  properly. 
An  excess  will  cause  as  much  trouble  as  an  insufficient  quantity. 
Blowholes  may  be  increased  in  size  and  number  by  using  too  much 
flux.  Also  the  molten  iron  will  incorporate  certain  constituents 
of  the  flux  if  it  is  applied  in  excess.  The  amount  to  be  applied  depends 
upon  the  flux  used.  A  welder  must  learn  to  know  his  flux  as  well 
as  his  blowpipe. 

The  powder  should  be  applied  regularly  by  dipping  the  hot 
welding  rod  into  it.  The  quantity  adhering  is  sufficient.  Do  not 
throw  large  quantites  into  the  weld  as  plenty  will  be  added  by  the 
welding  rod. 

Preparation  of  Welds.  All  cast  iron  over  J  inch  in  thickness 
should  be  beveled  or  chamfered  before  welding.  If  this  is  not  done, 
it  is  necessary  that  the  metal  be  burned  out  by  the  blowpipe  in  order 
that  complete  penetration  be  assured.  This  is  bad  practice  as  it  is 
almost  impossible  to  do  it  without  either  changing  the  state  of  the 
metal  in  the  groove  due  to  the  forced  flame,  or  causing  partial  ad- 
hesion. The  chamfering  should  be  a  little  wider  than  on  other 
metals  for  the  reason  that  it  is  good  practice  to  introduce  as  much 
special  metal  from  the  welding  rod  as  possible. 

The  chamfering  can  be  done  by  various  means.  If  the  casting 
is  light  and  broken  in  two  pieces,  it  may  be  taken  to  an  emery  wheel 
and  the  edges  ground  off.  If  the  casting  is  too  heavy  to  move,  a 
portable  grinder  or  cold  chisel  and  air  or  hand  hammer  can  be  used. 
If  the  casting  is  only  cracked,  the  cold  chisel  and  air  or  hand  hammer 
are  the  most  satisfactory  tools  to  use. 

After  the  weld  has  been  beveled  satisfactorily,  the  adjacent 
metals  should  be  cleaned  about  \  to  \  inch  from  the  edge.  This 
is  important,  because  all  dust,  sand,  scale,  etc.,  should  be  removed 
from  the  welding  zone. 

To  Prevent  Crack  from  Extending.  If  the  defect  in  a  casting 
is  a  crack  that  shows  a  tendency  to  extend  upon  heating,  a  hole 
should  be  drilled  in  the  casting  a  short  distance  from  the  end  and 
in  the  direction  the  crack  would  follow.  The  crack  will  not  extend 
beyond  this  hole,  and  the  hole  can  be  very  easily  filled  in. 


OXY-ACETYLENE  WELDING  63 

Welding  Process.  Although  the  melting  point  of  cast  iron 
is  not  high,  the  total  heat  required  to  bring  it  to  fusion  is  great, 
therefore  a  blowpipe  of  large  size  is  used.  The  speed  of  welding 
is  increased  considerably,  and  the  selection  of  the  proper  size  blow- 
pipe is  influenced  by  the  extent  of  the  pre-heating. 

Cast  iron  melts  very  rapidly  after  the  fusing  point  is  once 
reached,  and  when  molten  is  extremely  fluid.  Because  of  this 
property,  the  welding  should  be  carried  on  horizontally,  otherwise 
the  metal  will  flow  toward  the  lowest  point.  This  is  not  desired, 
because  it  will  tend  to  produce  adhesion.  In  case  it  is  not  possible 
to  arrange  the  casting  so  that  the  weld  will  be  horizontal,  the  welding 
must  be  started  at  the  lower  end,  and  skill  must  be  used  to  prevent 
the  too  rapid  advance  of  the  molten  metal.  It  is  very  difficult  to 
produce  vertical  and  overhead  welds  because  of  the  fluidity.  In 
welding  thin  sections  of  cast  iron,  the  rapidity  with  which  it  melts 
and  its  fluidity  often  cause  the  metal  to  sink,  bulge  downward,  or 
drop  in.  Consequently,  it  is  necessary  that  close  observation  and 
careful  manipulation  be  used  on  this  kind  of  work. 

Flame.  The  incandescent  jet  of  the  oxy-acetylene  flame  should 
never  impinge  on  the  molten  metal.  The  tip  of  this  jet  should  be 
held  at  a  distance  of  f  to  J  inch  from  the  metal  according  to  the 
thickness.  The  molten  iron  is  seriously  influenced  by  the  high 
temperature  of  this  jet  and  may  become  oxidized  and  decarbonized. 
This  must  be  rigidly  observed  except  when  it  is  necessary  to  use 
the  jet  to  burn  out  sand  holes,  blowholes,  etc. 

Manipulation  of  Blowpipes  and  Welding  Rods.  Because  cast 
iron  fuses  rapidly  when  once  the  melting  point  is  approached  and 
the  molten  iron  is  extremely  fluid,  the  circular  or  oscillating  motion 
imparted  to  the  blowpipe  need  not  be  so  pronounced.  The  welding 
of  cast  iron  is  nothing  but  a  succession  of  overlapping  miniature 
pools,  or  puddles,  of  molten  metal. 

The  weld  is  started  by  playing  the  blowpipe  on  the  two  lower 
edges  of  the  weld.  The  flame  should  strike  the  weld  almost  perpen- 
dicularly, because  if  the  blowpipe  is  inclined,  the  flame  will  blow 
the  molten  metal  ahead  of  the  weld,  and  adhesion  will  result.  When 
at  the  proper  temperature,  these  edges  are  fused  together  without 
any  filling  material  by  the  aid  of  a  little  flux.  It  is  important 
that  this  first  operation  be  carefully  carried  out,  as  the  strength  of 


64 


OXY-ACETYLENE   WELDING 


the  weld  is  dependent  upon  a  good  bottom  and  top.  When  this 
first  fusion  has  been  successfully  obtained,  the  welding  rod  is  brought 
into  play  and  the  high  silicon  metal  is  added.  With  each  addition, 


Fig.  73.     Warm  Welding  Rod  Is  Dipped  into  the 
Flux  before  Each  Addition  to  the  Weld 


Fig.  74.     For  Cast-Iron  Welding,  Blow- 
pipe and  Welding  Rod  Are  Held  Almost 
Vertical 


the  welding  rod  is  previously  dipped  into  the  flux  can,  and  the 
adhering  flux  introduced  in  the  weld,  Fig.  73.  As  the  welding  of 
cast  iron  is  a  comparatively  rapid  procedure,  the  welding  rod  can 


Fig.  75.     Dirt  May  Be  Scraped  off  by  Means  of  the 
Welding  Rod 


Fig.  76.     Welding  Rod  Should  Not  Be 
Held  Too  Far  from  Welding  Zone. 


be  held  more  vertically  and  added  faster,  Fig.  74.  In  welding  "dirty" 
iron  it  is  sometimes  convenient  to  hold  the  rod  in  a  horizontal  position 
and  scrape  out  sand,  carbon,  or  any  other  dirt  by  means  of  the  rod 


OXY-ACETYLENE   WELDING  65 

as  soon  as  it  appears,  Fig.  75.  In  this  connection,  it  may  be  added 
that  the  welding  rod  should  be  used  constantly  to  work  out  impurities 
and  blowholes.  The  welding  rod  should  be  melted  as  much  as  possible 
in  the  molten  metal  of  the  weld.  It  should  be  plunged  into  this 
liquid,  and  the  fusion  carried  out  by  playing  the  flame  around  it. 
The  welding  rod  should  not  be  held  too  far  from  the  welding  zone, 
Fig.  76,  nor  should  it  be  added  to  the  weld  drop  by  drop  as  shown 
in  Fig.  77. 

As  a  section  of  the  weld  is  finished,  it  should  be  scraped  or  rubbed 
with  a  file  while  red  hot,  Fig.  78,  to  remove  the  film  of  flux,  scale, 
sand,  and  dust  that  is  present.  This  film  if  allowed  to  cool  becomes 
very  hard  and  is  quite  resistant  to  machine  tools.  Regardless  of  the 


Fig.  77.      Welding-Rod  Should  Not  Be  Fig.  78.     Scraping   Finished    Weld  with    File  to 

Added  Drop  by  Drop  Remove  Scale 

quality  of  metal  beneath  it,  many  welds  have  been  rejected  because 
of  the  hardness  of  this  superficial  surface. 

If  the  weld  is  carefully  executed  and  the  surface  is  cleaned, 
it  will  look  like  the  left  of  Fig.  79,  while  if  poorly  executed  and  not 
cleaned,  it  will  look  like  the  right  of  Fig.  79. 

Never  go  over  a  weld  the  second  time  if  it  can  be  avoided.  In 
case  it  is  absolutely  necessary,  always  add  fresh  metal  from  the 
welding  rod,  as  a  failure  to  do  this  will  cause  a  loss  of  silicon  in  the 
weld  and  destroy  its  value  to  the  metal. 

Always  perform  the  welding  as  fast  as  possible,  because  extended 
heating  will  tend  to  lower  the  silicon  content  of  the  weld,  with  the 
resultant  formation  of  hard  iron. 


66 


OXY-ACETYLENE  WELDING 


Blowholes.  Blowholes  occur  frequently  in  the  weld  and  are 
particularly  troublesome  if  in  the  bottom  of  the  weld.  Their  presence 
can  be  caused  by  mechanically  enclosed  gases  or  by  improper  blow- 
pipe handling.  When  blowholes  appear  in  the  weld,  they  should  be 
instantly  worked  out.  This  may  be  done  by  forcing  with  the  welding 
rod  and  applying  flux.  In  beginning  a  weld,  it  is  necessary  that 
the  presence  of  blowholes  be  guarded  against,  as  it  is  difficult  to  work 
out  a  blowhole  at  the  bottom  of  the  weld  after  it  is  finished.  Occasion- 
ally, in  going  over  a  weld,  a  blowhole  is  discovered;  this  must  first  be 


Fig.  79.     Appearance  of  Cast-Iron  Welds  That  Have  Been 
Properly  (left)  and  Poorly  (right)  Executed 

burned  out  by  the  white  jet  of  the  flame  and  then  worked  over  with 
the  welding  rod. 

After- Treatment.  The  rate  of  cooling  materially  influences  the 
structure  of  the  metal  in  the  weld.  If  rapid  cooling  is  allowed,  hard 
brittle  iron  is  produced.  If  slow  cooling  is  employed,  soft  gray 
iron  is  formed.  Internal  strains  and  stresses  may  be  distributed 
and  adjusted  or,  in  some  cases,  eliminated  by  proper  cooling  and 
annealing. 

Castings  which  are  not  large  or  which  it  has  not  been  necessary 
to  pre-heat  extensively  may  be  satisfactorily  annealed  by  playing 
the  blowpipe  on  the  weld  and  surrounding  metal  until  it  is  at  a 
bright  red  heat.  The  heated  portion  is  then  covered  with  asbestos 


OXY-ACETYLENE  WELDING  67 

paper,  cinders,  or  other  nonconducting  material  that  will  retain 
the  heat  and  protect  the  castings  from  air  currents.  For  small 
castings,  a  barrel  or  bin  of  hydrated  lime  and  fiber  asbestos  is  recom- 
mended. This  makes  a  convenient  arrangement  and  is  very  satis- 
factory as  an  annealing  agent. 

Where  it  is  necessary  to  heat  the  entire  casting  in  a  charcoal 
or  coke  fire,  the  same  temporary  furnace  used  for  pre-heating  may 
be  used  in  annealing.  After  the  welding  has  been  completed,  the 
casting  should  be  covered  over  with  hot  coals  and  ashes,  and  the 
furnace  should  be  bricked  up,  i.  e.,  all  large  air  ports  closed,  the  top 
covered  with  asbestos  paper,  and  the  casting  allowed  to  cool  with 
the  fire. 

The  castings  should  never  be  removed  from  the  annealing  fire 
until  they  are  entirely  cold.  This  is  imperative,  as  cold  air  currents 
on  the  warm  castings  may  cause  checks  or  cracks.  In  some  cases,  12 
to  24  hours  are  required  for  satisfactory  cooling. 

Use  of  Carbon  Blocks.  In  case  it  is  not  possible  to  line  up 
the  weld  horizontally,  or  it  is  necessary  to  fill  in  a  wide  hole,  carbon 
blocks  or  steel  plates  are  sometimes  used  to  dam  or  retard  the  flow 
of  the  metal. 

MALLEABLE-IRON  WELDING 

Malleable  Iron.  Malleable  cast  iron,  or  malleable  iron,  as  it 
is  commonly  called,  is  used  extensively  in  castings  where  toughness, 
malleability,  and  resistance  to  sudden  shock  are  required.  The 
characteristic  that  gives  malleable  iron  its  greatest  value  as  compared 
to  gray  iron  is  its  ability  to  resist  shocks.  Malleability  in  a  light 
casting,  J  inch  thick  and  less,  means  a  soft  pliable  condition  and 
the  ability  to  withstand  considerable  distortion  without  fracture, 
while  in  the  heavy  section,  J  inch  and  over,  it  means  the  ability 
to  resist  shock  without  bending  or  breaking. 

In  the  manufacture  of  malleable-iron  parts,  white  iron  castings 
are  packed  in  annealing  pots  with  suitable  material,  such  as  mill- 
scale,  borings,  etc.,  and  subjected  to  a  cherry  red  heat  for  from  48 
to  96  hours,  after  which  they  are  allowed  to  cool  slowly.  During 
this  annealing  process,  the  material  in  which  the  castings  are  packed 
absorbs  the  carbon  from  the  surface  of  the  casting.  In  this  way  the 
surface  becomes  really  a  steel,  while  the  inside,  or  core,  becomes 
gray  cast  iron. 


68  OXY-ACETYLENE  WELDING 

Fusion  Weld  Not  Possible.  When  malleable  iron  is  heated 
to  a  fusing  heat  the  malleable  properties  are  destroyed  and  cannot 
be  regained. 

Brazing  Malleable  Iron.  The  most  successful  method  of  joining 
malleable  iron  with  the  oxy-acetylene  blowpipe  is  by  brazing  with 
Tobin  bronze.  While  this  gives  a  joint  of  different  color,  yet  the 
strength,  malleability,  and  machining  qualities  are  satisfactory. 

The  two  pieces  to  be  joined  are  beveled  as  for  cast-iron  welding. 
The  edges  are  brought  to  a  point  just  below  fusion,  great  care  being 
taken  that  they  do  not  become  fused.  When  the  edges  are  at  the 
right  temperature,  a  rod  of  Tobin  bronze  is  fused  into  the  groove 
with  the  aid  of  a  good  brass  flux.  The  work  should  be  carried  out  by 
using  a  flame  having  a  slight  excess  of  acetylene  and  should  be  done 
as  rapidly  as  possible  to  prevent  oxidation  of  the  bronze. 

ALUMINUM  WELDING 

General  Considerations.  When  aluminum  approaches  its  melt- 
ing point,  it  does  not  change  color  in  ordinary  light,  but  retains  its 
silvery  appearance  even  when  in  the  molten  condition.  When 
molten,  it  is  very  fluid  and  is,  therefore,  rather  difficult  to  control 
under  the  welding  flame. 

Oxidation.  Aluminum  oxidizes  very  easily  when  in  a  molten 
condition,  forming  an  oxide  that  melts  at  about  5400°  F.  The  oxide, 
therefore,  cannot  be  penetrated  by  means  of  the  flame,  but  must 
be  removed  either  chemically  by  means  of  a  flux  or  mechanically 
by  means  of  a  paddle. 

Expansion  and  Contraction.  Because  of  the  high  heat  con- 
ductivity of  aluminum,  expansion  and  contraction  do  not  give  great 
difficulty  owing  to  localized  heating.  However,  because  aluminum 
expands  greatly  and  is  very  weak  when  at  high  temperatures,  con- 
traction strains  are  very  likely  to  produce  cracks  or  checks  unless 
the  work  is  allowed  to  cool  evenly  and  slowly.  It  is  advisable  to 
pre-heat  aluminum  castings  to  between  300°  and  400°  F.  to  aid  the 
distribution  of  the  heat  and  prevent  warping. 

Welding  Rod.  In  welding  sheet  aluminum,  such  as  automobile 
bodies,  the  welding  rod  should  be  clean  material  of  the  same  alloy 
as  the  sheets  that  are  being  welded.  If  wire  cannot  be  obtained 
of  the  same  composition  as  the  sheets,  narrow  strips  should  be 


OXY-ACETYLENE  WELDING  69 

sheared  from  the  sheets  themselves  and  used  for  a  filling  material. 
The  strips  should  be  sheared  about  as  wide  as  the  sheets  are  thick. 

For  aluminum  castings,  such  as  crank  cases,  a  good  grade  of 
aluminum  wire  about  J  inch  in  diameter  should  be  obtainecj.  Welders 
should  not  use  the  cheap  solders  or  very  low  fusing  cast  rods  that 
are  sometimes  sold,  and  for  which  great  claims  are  made.  The 
operator  will  readily  appreciate  that  when  these  materials  are  added 
to  the  weld  they  will  merely  adhere  to  the  sides,  because,  while  the 
filling  material  will  be  quite  fluid,  the  edges  of  the  weld  will  not  be  at 
a  fusing  temperature. 

Flux.  It  is  impossible  to  weld  sheet  aluminum  without  the 
use  of  a  good  flux  to  dissolve  the  oxide  and  float  it  to  the  top  as  a 
slag.  In  cast-aluminum  work  a  paddle  may  be  used  to  accomplish  this 
result,  but  such  a  device  is  not  practical  for  sheet  work.  The  flux 
may  be  applied  either  by  dipping  the  warm  welding  rod  into  the 
flux  powder  or  by  mixing  the  flux  with  water  to  form  a  paste  and 
applying  this  to  the  joints  by  means  of  a  brush.  Care  must  be  taken 
that  too  much  flux  is  not  used,  because  an  excess  will  produce  a 
porous  weld  and  one  with  a  poor  surface.  After  the  work  has  been 
completed  the  flux  should  all  be  washed  off  with  warm  water. 

Flame.  In  order  to  be  sure  that  an  oxidizing  flame  is  not 
being  used,  it  is  permissible  and  advisable  to  use  a  flame  showing 
a  slight  excess  of  acetylene.  This  flame  will  also  have  the  advantages 
of  being  slightly  larger  in  volume  than  the  neutral  flame  and  of  lower 
temperature,  this  last  feature  being  helpful,  especially  to  the  new 
operator. 

Sheet=Aluminum  Welding 

Sheet-aluminum  work  may  be  handled  very  similarly  to  sheet 
steel  as  regards  preparation  and  allowance  for  expansion  and 
contraction. 

Types  of  Joints.  For  light  sheets  under  ^  inch  the  flange 
weld  should  be  used.  The  butt  joint  may  be  successfully  made  on 
light  sheets  by  an  experienced  operator,  but  there  is  a  great  deal 
of  danger  of  burning  through  and  having  to  fill  up  holes,  which  will 
leave  a  poorly  finished  weld. 

For  sheets  above  YS  mcn  the  butt  weld  is  found  to  be  the  best, 
and  for  sheets  above  f  inch  the  edges  should  be  beveled  the  same 
as  for  steel  plates. 


70  OXY-ACETYLENE  WELDING 

Welding  Process.  Select  the  proper  size  blowpipe  and  welding 
rod,  a  good  flux,  and  arrange  the  work  for  welding.  Start  the  welding 
by  playing  the  secondary  flame  of  the  blowpipe  over  the  parts 
surrounding  the  weld,  to  warm  them  up  slightly.  If  the  flux  is  to 
be  applied  with  a  brush,  it  should  be  done  at  this  time,  because  the 
heat  will  evaporate  the  water  and  leave  the  solid  flux  evenly  dis- 
tributed over  the  weld.  Welding  should  then  be  started  from  J  to  1 
inch  from  the  end — not  at  the  end.  The  blow  pipe  should  be  handled 
about  the  same  as  for  steel  welding,  care  being  taken  that  the  inner 
cone  of  the  flame  does  not  come  in  contact  with  the  metal.  For 
very  thin  sheet  welding  it  is  not  necessary  to  give  the  circular  or 
oscillating  motion  to  the  blowpipe;  it  is  merely  necessary  to  move 
it  forward  in  a  straight  line. 

On  the  heavier  work,  however,  the  same  motions  should  be 
used  by  the  welding  operator  as  are  used  for  steel.  The  welding 
wire  is  best  held  directly  in  line  with  the  weld  and  always  in  contact 
with  the  metal  just  ahead  of  the  blowpipe.  If  the  wire  is  not  in  con- 
tact with  the  edges  when  they  become  molten,  they  will  be  likely 
to  curl  up  or  draw  away  instead  of  flowing  together.  After  the 
main  weld  has  been  completed,  the  operator  should  go  back  and 
weld  the  short  section  that  was  left  unwelded  at  the  very  beginning. 
After  the  work  has  cooled  the  flux  should  be  removed  by  washing 
off  with  warm  water. 

Re-Welding.  The  operator  should  be  careful  that  the  weld  is 
completed  as  he  goes  along,  so  that  he  will  not  have  to  go  back  to 
make  repairs  or  to  do  re-welding.  If  it  is  necessary  to  go  back  over 
a  weld,  cracks  or  checks  are  very  likely  to  result  because  of  the 
weak  condition  of  the  metal  when  it  is  at  a  fusing  temperature.  If 
it  is  necessary  to  re-weld  a  certain  portion  of  the  joint,  the  surface 
should  be  chipped  off  so  as  to  present  a  clean  surface  for  the  new 
filling  material  to  fuse  to.  Following  the  suggestions  already  made, 
the  seam  and  the  surrounding  surfaces  should  be  thoroughly  pre- 
heated before  the  welding  is  started  to  prevent  cracking  as  much 
as  possible. 

After- Treatment.  If  possible,  welds  in  aluminum  sheet  should 
be  reheated  evenly  to  equalize  any  internal  strains.  Then,  after  the 
weld  has  become  cold,  it  should  be  hammered  to  improve  the  grain 
of  the  metal. 


OXY-ACETYLENE  WELDING  71 

Cast  Aluminum  Welding 

Aluminum  Castings.  Most  aluminum  castings  are  alloys  of 
aluminum,  zinc,  and  copper;  the  alloy  being  added  to  the  aluminum 
to  give  it  a  higher  tensile  strength  and  increase  its  resistance  to 
shock.  The  welding  of  cast  aluminum  is  different  from  that  of 
sheet  aluminum  and  resembles  in  a  general  way  the  welding  of 
cast  iron.  Oxidation  is  taken  care  of  by  using  flux  or  by  scraping  the 
oxide  out  by  means  of  a  paddle.  The  second  method  is  faster  and 
is  the  one  preferred  by  most  operators. 

Paddle.  The  paddle  is  made  by  flattening  down  the  end  of  a 
J-inch  steel  rod  to  a  smooth  short  flat  blade  about  f  inch  wide. 
The  handle  may  be  left  straight  or  bent  to  suit  the  operator.  The 
paddle  should  be  used  only  when  just  below  a  red  heat.  If  it  is 
cold,  the  molten  metal  will  stick  to  it,  and  if  it  is  too  hot  it  will  burn 
and  the  metal  will  stick  to  the  roughened  surfaces. 

Preparation.  Sections  if  over  J  inch  in  thickness  should  be 
chamfered  before  the  welding  is  started.  Sections  thinner  than 
this  may  be  worked  without  beveling.  The  old  metal  may  be  scraped 
out  by  means  of  the  paddle  in  order  to  give  a  clean  bright  surface 
for  the  new  material  to  be  added  to. 

Pre=Heating.  Because  aluminum  alloy  castings  are  not  very 
ductile  and  are  weak  when  at  a  high  temperature,  expansion  and 
contraction  must  be  taken  care  of.  This  is  handled  in  the  same 
general  way  as  in  the  case  of  cast-iron  work.  The  casting  should 
be  pre-heated  either  partially  or  wholly  by  some  slow  heating  agent, 
such  as  a  gas  burner  or  mild  charcoal  fire.  The  pre-heating  should 
never  be  carried  to  too  high  a  temperature,  because  of  the  danger 
of  the  metal  sinking,  or  caving  in.  The  casting  will  be  sufficiently 
warm  for  welding  when  a  file  or  chisel  will  mark  it  easily,  or  when 
a  piece  of  dry  pine  stick  is  charred  upon  being  drawn  across  the 
heated  section. 

Welding  Process.  When  a  flux  is  used  in  welding  cast  alumi- 
num, the  work  is  carried  on  in  the  same  general  manner  as  in  welding 
cast  iron,  and  the  same  general  precautions  regarding  the  peculiari- 
ties of  the  metal  are  to  be  observed  as  in  welding  sheet  aluminum. 

If  a  paddle  is  used  to  break  the  film  of  oxide  and  scrape  it  out  of 
the  weld,  the  edges  are  brought  to  a  state  of  fusion  for  a  length  of 
about  1  or  1 J  inches.  The  paddle  is  then  used  to  scrape  out  the  weld 


72  OXY-ACETYLENE  WELDING 

to  make  a  slight  bevel  and  present  clean  surfaces  for  the  filling  mate- 
rial to  be  added  to.  The  welding  rod  is  then  introduced  into  this 
groove.  The  paddle  is  used  continually  to  work  in  the  filling  material, 
scrape  off  any  oxide  that  forms,  and  then  to  smooth  off  the  surface 
of  the  weld.  After  a  small  section  of  the  joint  has  been  completed, 
the  casting  is  turned  over,  and  the  weld  for  this  length  is  smoothed  off 
on  the  underside  by  means  of  the  blowpipe  and  paddle.  The  welding 
is  carried  on  in  this  manner,  section  by  section,  until  the  entire  joint 
is  completed.  If  the  weld  were  completed  on  the  first  side  and  then 
turned  over  and  smoothed  its  entire  length  on  the  underside,  cracks 
would  develop,  and  the  casting  would  warp  out  of  shape. 

After=Treatment.  When  the  welding  has  been  completed,  the 
casting  should  be  reheated  slightly  to  remove  any  local  strains  and 
should  then  be  covered  over  with  asbestos  paper  to  protect  it  from 
drafts  and  to  allow  it  to  cool  very  slowly.  If  the  cooling  is  carried  on 
rapidly,  or  if  air  currents  are  allowed  to  strike  the  casting,  it  will  very 
likely  crack  either  in  the  weld  or  some  weak  section. 

COPPER  WELDING 

General  Considerations.  Because  of  the  high  thermal 
conductivity  of  copper,  the  heat  from  the  blowpipe  is  conducted 
back  into  the  work  rapidly  and  is  lost  to  the  weld.  This  necessitates 
the  use  of  a  large  size  welding  head  or  the  use  of  an  auxiliary  source 
of  heat  to  assist  the  welding  flame  in  the  case  of  heavy  work.  When 
at  high  temperatures,  copper  is  weak  in  tensile  strength  the  same 
as  aluminum.  Because  of  these  two  factors  the  effects  of  expansion 
and  contraction  must  be  carefully  considered,  so  that  the  work  will 
not  cool  too  rapidly  after  the  welding  has  been  completed,  and  will 
not  crack  at  high  temperatures. 

Oxidation.  Copper  oxidizes  quite  readily,  forming  an  oxide 
which  dissolves  in  the  molten  metal  and  changes  the  structure  of 
the  weld.  The  amount  of  oxide  that  can  be  absorbed  is  very  high, 
consequently  great  care  must  be  exercised  to  keep  the  absorption 
at  a  minimum.  Welding  rods  containing  a  small  percentage  of 
phosphorus  and  suitable  fluxes  are  used  to  counteract  the  oxide  and 
reduce  it  as  much  as  possible. 

Welding  Rod.  For  successful  copper  welding,  it  is  necessary 
to  use  electrolytic  copper  containing  about  one  per  cent  phosphorus, 


OXY-ACETYLENE  WELDING  73 

supplied  in  coils  and  drawn  rods.  The  cast  copper  alloy  rods  that 
are  on  the  market  are  not  satisfactory,  because  the  structure  and 
composition  will  vary  even  in  a  single  rod  to  such  an  extent  that  a 
homogeneous  weld  cannot  be  made. 

Flux.  In  welding  copper  the  flux  is  used  not  only  to  cleanse 
the  weld,  but  also  to  protect  the  metal  adjacent  to  the  welding  zone 
from  the  gases  of  the  flame.  When  welding  sheet  copper  it  is  advisable 
to  make  a  paste  of  the  flux  by  adding  water  and  to  coat  the  metal 
about  one  inch  adjacent  to  the  edge  of  the  weld.  When  this  flux  is 
melted,  it  will  form  a  glassy  film  that  will  protect  the  metal  from  the 
gases  of  the  flame  and  the  air  surrounding  the  work.  Additional 
flux  is  added  to  the  weld  as  the  work  progresses,  by  dipping  the 
warm  rod  into  the  dry  flux,  as  in  welding  other  materials. 

Flame.  It  is  very  important  that  the  neutral  flame  be 
maintained  at  all  times,  and  the  operator  should  use  great  care  in 
adjusting  his  gases,  so  the  flame  will  not  have  an  excess  of  acetylene 
nor  be  oxidizing.  Because  of  the  peculiar  properties  of  the  metal, 
the  gases  of  the  reducing  flame  are  very  likely  to  be  absorbed,  and 
because  of  the  ease  with  which  the  metal  oxidizes,  oxidation  is 
liable  to  occur  if  the  flame  contains  an  excess  of  oxygen. 

Preparation.  Sheets  that  are  less  than  J  inch  in  thickness 
may  be  butted  together  without  beveling.  Sheets  heavier  than 
this  should  always  be  beveled,  and  no  attempt  should  be  made 
to  depend  upon  the  flame  to  penetrate  the  heavier  thicknesses.  In 
all  cases  of  copper  welding,  the  edges  to  be  joined  and  the  material 
adjacent  to  the  edges  should  be  scraped  or  filed  to  present  a  clean 
surface  for  the  filling  material  to  be  added  to. 

Welding.  The  edges  of  the  metal  surrounding  the  weld  should 
be  raised  to  a  fairly  high  temperature  before  the  actual  welding  is 
started.  On  small  pieces  and  light-weight  work,  this  may  be  done 
by  means  of  the  welding  blowpipe,  but  for  heavy  work  and  long 
welds,  it  is  best  to  do  this  by  means  of  a  gas  or  oil  pre-heating  burner. 
After  the  work  has  been  brought  to  a  high  temperature,  the  welding 
should  be  started  at  one  end  and  should  be  performed  as  rapidly 
as  possible.  The  welding  rod  and  edges  of  the  weld  should  reach 
the  state  of  fusion  at  the  same  time,  so  as  to  prevent  adhesion  and 
to  insure  a  good  weld.  This  feature  is  harder  to  accomplish  in  welding 
copper  than  in  other  metal,  because  the  heat  is  conducted  back  into 


74  OXY-ACETYLENE  WELDING 

the  rod  or  into  the  work  very  rapidly,  necessitating  very  careful 
and  skillful  manipulation  of  the  blowpipe  and  rod.  The  blowpipe 
should  be  held  almost  vertical,  about  the  same  as  in  the  case  of 
cast-iron  welding.  If  held  at  too  great  an  angle,  the  molten  metal 
will  be  blown  ahead  and  will  adhere  to  the  cold  edges  of  the  weld 
in  advance  of  the  blowpipe.  The  inner  cone  of  the  flame  should 
never  come  in  contact  with  the  metal,  but  should  be  held  about 
J  or  1  inch  above  the  surface  of  the  weld  to  prevent  burning  the 
metal.  The  oscillating  motion  should  be  carried  on  about  the  same 
as  in  steel  welding  but  a  little  more  rapidly,  and  should  consist  of 
smaller  circles.  The  welding  rod  should  be  plunged  into  the  molten 
metal  all  the  time  and  should  be  continuously  moved  around  or 
stirred,  so  that  it  will  be  thoroughly  incorporated  and  will  bring  the 
oxide  and  slag  to  the  surface.  The  weld  should  be  built  up  above 
the  surface  of  the  sheets,  so  there  will  be  enough  material  to  allow 
for  hammering  after  the  welding  has  been  completed.. 

Re-Welding.  In  case  it  is  necessary  to  re-weld  a  portion  of  the 
joint,  it  is  necessary  that  the  old  material  be  chipped  out  and  new 
material  added. 

After=Treatment.  After  the  welding  operation  has  been 
completed,  the  work  should  be  heated  very  carefully  and  evenly 
until  it  is  almost  at  a  bright  red  heat.  The  weld  should  then  be 
hammered  while  hot,  so  that  the  strength  of  the  joint  will  be  increased 
as  much  as  possible.  After  the  hammering  has  been  finished,  the 
work  should  be  again  reheated  to  a  red  heat  and  cooled  quickly 
by  means  of  an  air  blast  or  chilled  by  plunging  in  water.  Care  must 
be  exercised  in  this  operation  if  the  work  be  a  casting  having  confined, 
or  rigid  members,  so  that  .cracking,  or  checking,  does  not  occur. 

BRASS  AND  BRONZE  WELDING 

General  Considerations.  Brass  and  bronze  are  both  alloys  of 
copper,  brass  consisting  mainly  of  copper  and  zinc,  and  bronze 
of  copper  and  tin.  Both  brass  and  bronze  are  welded  in  about  the 
same  general  manner  as  copper,  but  because  of  the  peculiar  properties 
of  the  alloying  metals,  zinc  and  tin,  it  is  necessary  that  they  receive 
certain  variations  in  welding. 

Oxidation.  In  both  brass  and  bronze,  the  alloying  metal  is 
greatly  affected  by  the  high  temperature  of  the  flame,  and  the  material 


OXY-ACETYLENE  WELDING  75 

will  be  subject  to  a  loss  of  zinc  or  tin,  unless  proper  precautions  are 
taken.  These  metals  will  combine  with  the  oxygen  and  pass  off  as 
white  vapor,  and  leave  a  weld  of  different  composition  and  color. 

Absorption  of  Gases.  The  molten  metal  in  both  brass  and  bronze 
absorbs  certain  gases  very  readily,  and  unless  this  absorption  is 
counteracted,  the  weld  will  be  spongy  and  weak.  This  may  be  taken 
care  of  by  using  a  suitable  welding  rod  and  flux. 

Welding  Rod.  Because  of  the  varying  composition  of  brass 
and  bronze,  and  because  of  the  loss  of  the  alloying  elements  when 
welding,  it  is  practically  impossible  to  produce  welds  of  the  same 
color  as  the  original  material.  When  welding  brass,  a  good  grade 
of  drawn  brass  will  be  found  most  satisfactory,  and  in  the  case  of 
bronze,  a  good  drawn  bronze,  such  as  manganese  or  Tobin  bronze. 
The  cast  rods  that  are  on  the  market  are  not  satisfactory,  because  it  is 
quite  impossible  to  cast  a  rod  having  the  same  composition  throughout. 

Flux.  The  flux  used  for  brass  and  bronze  is  practically  the 
same  as  that  used  for  copper.  It  should  be  applied  by  dipping  the 
warm  welding  rod  into  the  powder  and  adding  it  to  the  weld  in  this 
manner.  It  is  not  necessary  to  use  as  much  flux  as  in  welding  pure 
copper,  and  care  must  be  taken  that  an  excess  is  not  used,  because  the 
weld  may  become  porous. 

Flame.  A  neutral  flame  must  be  maintained  at  all  times  for 
the  same  reasons  as  explained  under  copper  welding.  The  blowpipe 
should  be  held  between  J  to  J  inch  from  the  metal.  If  the  flame 
is  held  too  close  in  the  case  of  bronzes,  the  concentrated  heat  will 
cause  a  segregation  or  separation  of  the  tin  from  the  copper,  and 
it  will  be  practically  impossible  to  again  unite  these  elements. 

Preparation.  The  edges  of  the  metal  for  a  thickness  of  less 
than  |  inch  may  be  merely  butted  together  and  welded,  while  for 
metals  above  this  thickness  the  edges  should  be  beveled  or  cham- 
fered, so  as  to  allow  penetration  of  the  flame  and  insure  a  good  weld. 

Welding.  Because  of  the  high  conductivity  of  these  materials, 
it  is  best  that  they  be  pre-heated  to  bring  them  to  a  suitable  condition 
for  rapid  welding.  Care  must  be  taken  when  pre-heating  bronze 
that  it  does  not  get  too  hot,  because  it  is  weak  at  high  temperatures 
and  is  liable  to  break  or  crack  under  its  own  weight.  The 
welding  is  carried  on  in  about  the  same  manner  as  for  copper,  and 
the  blowpipe  is  handled  in  practically  the  same  way.  The  welding 


76 


OXY-ACETYLENE  WELDING 


rod  should  be  in  contact  with  the  edges  of  the  metal  at  all  times, 
and  the  blowpipe  should  be  played  constantly  on  both  the  rod  and 
the  edges  of  the  metal  to  keep  them  at  the  same  temperature  in  order 
that  adhesion  may  be  prevented. 

Re-Welding.  Re-welding  should  be  avoided,  but  if  it  is 
absolutely  necessary  to  re-weld  the  work,  the  section  should  be 
chipped  out,  and  new  material  added,  as  in  the  case  of  copper. 

After=Treatment.  Both  brass  and  bronze  should  be  annealed 
after  welding  by  reheating  evenly,  and  then  allowed  to  cool  slowly. 
Brass  may  be  improved  by  hammering  before  the  final  annealing. 
Brass  of  low  zinc  content,  i.e.,  red  brass,  should  be  hammered 
while  hot,  while  brass  of  high  zinc  content,  i.e.,  yellow  brass, 
should  be  hammered  cold. 

MISCELLANEOUS   PROCESSES 

CUTTING 

Cutting  In  Automobile  Repairs.  The  oxy-acetylene  cutting 
blowpipe  finds  considerable  application  in  the  automobile  repair 
shop  for  beveling  the  ends  of  shafts 
and  other  pieces  of  work  preparatory 


Fig.  80.     Beveling    Round    Shaft  for  Welding. 
The  other  piece  is  on  the  table 


Fig.  81.     Beveling  End  of  Heavy 
Square  Shaft  for  Welding 


to  welding,  Figs.  80  and  81,  cutting  reinforcing  plates  out  of  large 
sheets  for  frame  repairs,  altering  chassis,  etc.,  Fig.  82.     The  cutting 


OXY-ACETYLENE  WELDING 


77 


blowpipe  is  capable  of  doing  this  work  cheaply  and  quickly,  two 
necessary  factors  for  the  successful  first-class  repair  shop. 

Principle  of  Cutting  with  Oxygen.  At  ordinary  temperatures, 
steel  oxidizes  in  the  air,  forming  what  is  commonly  called  "rust". 
At  a  white  heat  it  will  oxidize  more  rapidly,  as  is  seen  in  the  black- 
smith shop  when  pieces  are  brought  to  a  very  high  temperature. 
When  steel  is  heated  to  a  red  heat,  and 
a  stream  of  pure  oxygen  is  directed  on 
it,  the  oxidation  takes  place  more  rap- 
idly and  more  violently  and  is  restricted 
to  the  locality  upon  which  the  stream 
of  oxygen  is  played.  This  localized  oxi- 
dation is  the  basis  upon  which  the  oxy- 
acetylene  cutting  blowpipe  operates. 

Metals  That  Can  Be  Cut.  Steel  and 
wrought  iron  are  the  only  metals  that 
can  be  cut  successfully  by  means  of 
the  oxygen  jet.  Although  cast  iron,  cop- 
per, brass,  bronze,  aluminum,  etc.,  oxi- 
dize easily,  nevertheless  they  cannot 
be  cut. 

When  the  oxygen  combines  with 
the  iron,  heat  is  generated.  This  heat 
of  formation,  with  the  aid  of  the  heat 
supplied  by  the  pre-heating  flames  of 

the  blowpipe,  brings  the  oxide  to  a  molten  condition.  The  molten 
oxide  either  flows  or  is  blown  out  of  the  cut  and  leaves  a  fresh 
thoroughly  heated  line  through  the  metal  for  the  further  action 
of  the  cutting  oxygen.  In  the  case  of  steel  and  wrought  iron,  the 
oxide  melts  at  a  much  lower  temperature  than  the  material  being 
cut  and  therefore  blows  out  without  melting  the  surface  of  the 
material.  In  the  cases  of  cast  iron  and  certain  alloy  steels,  the 
melting  temperature  of  the  oxide  is  as  high  and  in  some  cases 
higher  than  that  of  the  metal,  and  therefore  melts  the  edges  or 
freezes  in  the  kurf  and  so  hinders  the  cutting.  Also,  in  the  case 
of  some  of  these  materials,  the  heat  of  formation  produced  by  the 
combination  of  the  oxygen  with  the  metal  is  not  sufficient  to  carry 
the  cut  through  the  thickness  of  the  work. 


Fig .  82 .   Cutting  Reinforcing  Plate 

Out  of  Large  Sheet  Steel  for 

Frame  Repair 


78 


OXY-ACETYLENE  WELDING 


Necessary   Cutting   Apparatus.    A   complete   cutting   station, 
Fig.  83,  consists  of  the  following  apparatus: 

Cutting  blowpipe  with  set  of  cutting  nozzles 
Oxygen  cutting  regulator  with  two  gages 
Acetylene  regulator  with  one  or  two  gages 
Adapter  for  acetylene  cylinder 
One  length  high-pressure  rubber  hose  for  acetylene 
One  length  copper  armoured  hose  for  oxygen 
Darkened  spectacles,  wrenches,  hose  clamps,  etc. 

Cutting     Blowpipe. 

In  the  cutting  blowpipe, 
Fig.  9,  page  9,  there 
are  usually  six  small 
oxy-acetylene  flames  sur- 
rounding a  center  orifice 
through  which  pure  oxy- 
gen is  directed.  The  six 
heating  jets  are  used 
only  for  the  purpose  of 
bringing  the  edge  of  the 
material  to  a  tempera- 
ture at  which  the  jet  of 
pure  oxygen  will  unite 
rapidly  with  the  steel, 
as  explained  above. 

Cutting  Nozzle. 
There  are  usually  four 
sizes  of  cutting  nozzles 
furnished  for  handling 
work  of  various  thick- 
nesses, from  very  thin 
plate  up  to  material  14 
and  16  inches  thick. 
Besides  these,  some 
manufacturers  also  fur- 
nish what  is  known  as 
a  "rivet  cutting  nozzle". 

This  is  a  thin  flat  nozzle  that  can  be  laid  against  the  sheet,  allowing, 

the  rivet  head  to  be  cut  off  close  to  the  sheet. 


Fig.  83.    Cutting  Unit  for  Use  with  Acetylene  in  Cylinders, 

Mounted  on  Emergency  Truck 
Courtesy  of  Oxweld- Acetylene  Company,  Chicago 


OXY-ACETYLENE  WELDING  79 

Working  Pressure.  The  necessary  pressures  of  the  gas  that  are 
required  by  the  different  sizes  of  cutting  nozzles  and  for  the  different 
thicknesses  of  material  are  given  by  the  manufacturers.  It  is  very 
important  that  the  operator  use  these  pressures  instead  of  higher 
pressures  because  of  the  increased  amount  of  oxygen  used  and  the 
consequent  high  cost  of  operation,  also  because  the  cut  will  not  be 
smooth  if  too  much  oxygen  is  used. 

Care  of  Blowpipe.  If  the  blowpipe  is  handled  properly  there 
will  be  very  little  deterioration.  It  should  only  be  necessary  to 
clean  the  replaceable  and  working  parts,  repack  the  valves,  and 
occasionally  ream  out  and  true  up  the  nozzles.  Care  should  be  taken 
that  the  orifices  of  the  nozzles  do  not  become  enlarged  by  reaming, 
because  the  heating  jets  will  be  made  thicker  and  shorter  and  the 
cutting  jet  will  spread  rather  than  leave  the  blowpipe  as  a  long 
thin  stream. 

The  blowpipe  may  be  cleaned  the  same  as  the  welding  blow- 
pipe by  removing  both  the  acetylene  and  oxygen  hose  and  connecting 
the  nozzle  to  the  oxygen  hose,  Fig.  16,  page  18,  and  turning  on  the 
oxygen  to  a  pressure  of  about  20  pounds  per  square  inch,  having 
first  the  cutting  oxygen  valve  open,  then  the  acetylene  needle  valve, 
and  lastly  the  oxygen  needle  valve.  This  will  allow  the  large  particles 
to  be  blown  out  of  the  larger  passages  before  they  have  a  chance 
to  clog  up  the  smaller  passages. 

Regulators.  The  cutting  regulator,  in  principle,  is  the  same  as 
that  described  on  page  20,  but  in  size  it  is  much  larger  than  the 
welding  regulator  and  is  capable  of  both  a  higher  delivery  pressure 
and  a  greater  volume. 

The  acetylene  regulator  is  the  same  as  is  used  in  the  welding 
equipment,  and  described  on  page  20. 

Care  of  Apparatus.  The  blowpipe,  regulators,  and  hose  should 
receive  the  same  care  and  attention  as  is  explained  for  the  welding 
apparatus  on  pages  18  to  21. 

Instructions  for  Connecting  Apparatus.  The  regulators  and  the 
blowpipe  are  connected  up  in  the  same  manner  as  the  welding 
apparatus,  and  therefore  the  operator  is  referred  to  pages  22  to  23 
for  instructions. 

How  To  Light  the  Blowpipe.  (1)  Take  the  blowpipe  in  hand 
and  open  the  oxygen  cutting  valve  fully. 


80  OXY-ACETYLENE  WELDING 

(2)  Turn  the  oxygen  pressure-adjusting  screw  to  the  right 
until  the  required  pressure  for  the  work  to  be  done  shows  on  the 
low-pressure  gage.     (See  the  maker's  chart  for  the  correct  pressure.) 

(3)  Close  the  oxygen  cutting  valve. 

(4)  Open  the  acetylene  needle  valve  fully. 

(5)  Turn  the  acetylene  pressure-adjusting  screw  to  the  right 
until  a  good  jet  of  acetylene  issues  from  the  heating  orifices.     In 
the  case  of  pressure  blowpipes,  until  the  required  pressure  for  the 
thickness  to  be  cut  shows  on  the  low-pressure  gage.    (See  the  maker's 
chart  for  the  correct  pressure.) 

6.  Open  the  oxygen  needle  valve  one-quarter  turn  and  light 
the  blowpipe  by  means  of  the  pyro-lighter  that  is  usually  furnished. 

NOTE — A  back-fire  might  occur  if  there  is  not  enough  acetylene  being 
supplied.  If  this  occurs  increase  the  acetylene  supply  by  turning  the  acetylene 
pressure-adjusting  screw  farther  to  the  right. 

7.  Adjust  the   acetylene  pressure-adjusting  screw  to  give  a 
slight  excess  of  acetylene  to  the -flame. 

8.  Adjust  the  acetylene  needle  valve  to  give  a  neutral  flame 
(see  under  Flame  Regulation,  page  25)   when  the  cutting  oxygen 
valve  is  open. 

To  Shut  off  the  Blowpipe.  In  the  case  of  the  injector  type  of 
blowpipe,  first  close  the  acetylene  needle  valve  and  then  the  oxygen 
needle  valve. 

In  the  case  of  pressure  blowpipes,  first  close  the  oxygen  needle 
valve  and  then  the  acetylene  needle  valve. 

To  Cut.  With  the  cutting  valve  closed  apply  the  heating  flames 
to  the  edge  of  the  metal,  keeping  the  nozzle  at  such  a  distance  that 
the  small  flames  barely  touch  the  metal.  As  soon  as  the  metal 
becomes  heated  to  a  cherry  red,  open  the  cutting  valve,  raise  the 
blowpipe  slightly  to  increase  the  distance  between  the  nozzle  and 
metal,  and  then  move  it  along  the  surface  as  fast  as  a  distinct  and 
and  clear  kurf  can  be  secured.  The  blowpipe  should  be  held  at  a 
constant  distance  from  the  work.  It  should  travel  away  from  the 
operator  in  order  that  he  may  watch  the  cut  advance. 

Back=Firing.  Occasionally,  particles  of  molten  metal  will 
impinge  on  the  nozzle  of  the  blowpipe,  or  the  operator  will  allow 
the  nozzle  to  touch  the  surface  of  the  metal,  and  the  blowpipe  will 
back-fire.  When  this  occurs,  first  close  the  acetylene  needle  valve 


OXY-ACETYLENE  WELDING  81 

and  allow  oxygen  to  clear  the  passage,  then  open  the  acetylene 
needle  valve  fully  and  relight.  If  the  back-firing  continues,  close 
both  the  acetylene  and  oxygen  needle  valves,  cool  the  blowpipe  by 
plunging  in  water  and  relight.  Other  causes  of  back-firing  are 
loose  internal  and  external  nozzles  or  dirt  on  the  nozzle  seat.  These 
can  be  eliminated  by  tightening  the  nozzles  and  cleaning  the  seat. 
These  back-fires  are  usually  only  a  series  of  pops  or  sharp  reports, 
and,  as  a  rule,  will  not  extinguish  the  flame. 

Notes  on  Cutting.  Heating  Flames.  The  heating  flames 
should  be  small  to  produce  smooth  cutting.  If  the  flames  are  too 
small,  the  blowpipe  is  liable  to  back-fire.  If  they  are  large,  the  top 
edges  of  the  cut  will  melt  and  produce  a  rough  cut. 

Speed  of  Cutting.  The  speed  of  the  blowpipe  travel  should  be 
slow  enough  to  allow  the  oxygen  jet  to  penetrate  yet  not  so  slow 
that  the  oxygen  will  be  wasted. 

Restarting  Cut.  If  the  blowpipe  travels  too  fast,  and  the  cut 
is  "lost",  it  is  necessary  to  shut  off  the  cutting  oxygen  and  apply  the 
heating  flames  to  the  point  of  stopping  until  the  metal  is  hot  enough 
to  start  the  cut  again. 

To  Cut  Round  Shafts,  Etc.  The  cutting  of  round  pieces  will 
be  made  easier  if  the  surface  of  the  work  is  first  chipped  with  a  chisel. 
This  will  present  a  good  edge  for  the  cutting  blowpipe  to  bite  on. 

To  Pierce  Holes.  When  piercing  holes,  a  high  oxygen  pressure 
is  necessary,  and  the  metal  must  be  brought  to  fusion  before  the 
cutting  oxygen  is  employed.  The  blowpipe  is  held  at  a  slight  angle  so 
the  sparks  will  be  blown  out  of  the  hole  and  away  from  the  blowpipe. 

Cutting  Dirty  and  Poor  Material.  If  there  is  considerable  rust, 
scale,  paint,  etc.,  on  the  surface,  the  cutting  will  be  interfered  with 
by  small  particles  flying  against  the  end  of  the  nozzle  and  perhaps 
causing  back-firing.  To  overcome  this,  the  heating  flames  may  be 
made  longer,  allowing  the  blowpipe  to  be  held  farther  away  from 
the  surface,  or  the  scale  or  paint  may  be  removed  by  first  passing 
the  flame  over  the  line  of  cutting  before  the  cutting  is  started. 

LEAD  BURNING 

Different  Methods.  Formerly,  lead  burning,  or  lead  welding, 
was  confined  to  garages  and  service  stations  that  catered  to  the  electric 
automobile  only,  but  since  the  introduction  of  electric  lighting  and 


82 


OXY-ACETYLENE   WELDING 


starting  batteries  for  gasoline  automobiles,  lead  burning  has  become 
one  of  the  works  of  the  repair  man  in  all  garages.  It  is  therefore 
important  that  the  repair  man  have  a  sufficient  knowledge  of  this 
class  of  work  to  enable  him  to  handle  any  work  of  this  nature  that 
may  happen  to  come  into  his  shop. 

Up  to  the  time  of  the  recent  development  of  a  very  small  oxy- 
acetylene  blowpipe  for  lead-burning  work,  the  hydrogen  air  burner 
was  used  by  most  lead  burners.  The  oxy-acetylene  blowpipe,  how- 


Fig.  84.     Oxy-Acetylene  Lead  Burning  Apparatus 
Courtesy  of  Oxweld  Acetylene  Company,  Chicago 

ever,  is  rapidly  supplanting  the  old  method  and,  as  a  matter  of  fact, 
within  two  years  it  has  become  universally  accepted  as  being  far 
superior  to  the  old  method  in  handiness  of  operation,  speed,  and 
consequent  economy,  and  has  been  adopted  by  the  large  battery 
makers  in  both  their  factories  and  service  stations. 

When  an  operator  accustomed  to  the  old  flame  tries  the  oxy- 
acetylene  blowpipe,  he  is  very  likely  to  discredit  it  at  first  and  claim 
that  it  is  not  satisfactory.  However,  every  operator  who  gives  the 
oxy-acetylene  lead-burning  blowpipe  a  fair  trial  and  uses  it  in 
accordance  with  the  methods  recommended  by  the  manufacturers 


OXY-ACETYLENE  WELDING  83 

of  the  apparatus  must  acknowledge  it  as  being  superior  to  any 
method  he  has  ever  used.  Its  advantages  are  emphasized  even  more 
emphatically  if  he  returns  to  the  old,  slower,  and  more  costly  methods. 
Lead=Burning  Apparatus.  A  complete  lead-burning  station 
for  use  with  oxygen  and  acetylene,  Fig.  84,  consists  of  the  following 
apparatus : 

Lead-burning  blowpipe  with  set  of  tips 

Oxygen  regulator  with  low-pressure  gage 

Acetylene  regulator  with  low-pressure  gage 

Adapter  for  acetylene  cylinder 

Valve-block 

Two  lengths  of  high-pressure  hose  to  connect  regulators  to  valve  block 

Two  lengths  of  small  hose  to  connect  blowpipe  to  valve  block 

Lead-Burning  Blowpipe.  To  make  the  blowpipe  as  light  in 
weight  and  as  handy  as  possible  there  are  no  large  valves.  Instead, 
a  valve  block  is  furnished  for  regulating  the  gases,  which  may  be 
attached  to  a  bench  or  a  wall.  In  order  to  make  minor  or  finer 
adjustments  of  the  flame,  and  to  allow  various  size  tips  to  be  used 
on  the  blowpipe  and  still  maintain  a  perfect  flame,  an  adjustable 
injector  is  provided  at  the  top  of  the  blowpipe  within  reach  of  the 
operator's  fingers. 

Tips.  There  are  about  five  sizes  of  tips  supplied  for  use  on 
different  thicknesses  and  various  classes  of  work,  each  giving  its 
own  special  size  flame.  The  oxygen  consumption  of  the  various 
size  tips  ranges  from  |  to  6  cubic  feet  per  hour.  For  storage-battery 
work  the  average  consumption  is  about  2  cubic  feet  per  hour. 

Regulators.  The  regulators  supplied  with  lead-burning  apparatus 
operate  on  the  same  principle  as  the  regulator  described  on  page  19, 
the  only  difference  being  that  they  are  of  smaller  size  and  especially 
adapted  to  small  flames. 

Operation  of  Lead=Burning  Apparatus.  The  apparatus  is 
connected  in  the  same  general  manner  as  the  welding  apparatus 
for  which  instructions  are  given  on  pages  22  to  26.  The  needle 
valves  on  the  valve  block  are  used  to  obtain  approximate  adjust- 
ment of  the  flame,  and  then  the  small  thumb-nut  on  the  blowpipe 
is  used  to  make  the  finer  adjustment.  The  pressure-adjusting 
screws  should  be  set  to  give  pressures  of  about  10  pounds  per 
square  inch  for  the  oxygen,  and  2  pounds  per  square  inch  for 
the  acetylene. 


84 


OXY-ACETYLENE  WELDING 


The  blowpipe,  regulators,  hose,  etc.,  should  receive  the  same  care 
and  attention  as  the  welding  apparatus  and  for  which  suggestions 
are  given  on  pages  18  to  21. 

Lead=Burning  Process.  The  oxy-acetylene  blowpipe  should  be 
handled  in  such  a  manner  that  the  flame  strikes  the  work  perpen- 
dicularly. If  the  blowpipe  is  used  on  a  slant,  the  inner  cone  will 
not  bring  the  work  to  the  fusing  temperature  as  rapidly  as  if  held 
vertically,  and  the  secondary  flame,  or  outer  envelope,  will  be  very 
likely  to  heat  the  surrounding  metal  to  such  a  temperature  that  it 
will  give  way  and  break  under  its  own  weight.  When  working  with 

the  oxy-acetylene  flame  on  stor- 
age batteries  and  the  like,  the 
operator  should  do  the  burning 
quickly.  He  should  bring  the 
flame  down  to  the  work,  fuse  the 
metal,  add  the  necessary  burn- 
ing bar,  or  filling  wire,  smooth 
off  the  work,  and  remove  the 
flame,  all  as  rapidly  as  possible. 
Burning  Terminal  Groups. 
When  burning  plates  to  terminal 
bars,  a  small  flame  should  be 
used,  and  the  work  should  be 
held  in  a  fixture,  as  shown  in 
Fig.  85.  The  small  ends  on  the 
plates  should  extend  up  into  the 
terminal  bar  slots  about  two- 
thirds  of  the  way.  The  burning  should  be  carried  on  by  first  fusing 
the  ends  of  the  plates  to  the  bottom  of  the  slots,  then  filling  up  the 
rest  of  the  slot  by  adding  lead  from  a  coil  of  wire  or  a  burning  bar. 
After  the  several  plates  have  been  burned  on  in  this  way,  the  flame 
should  be  moved  perpendicularly  over  the  surface  to  smooth  it  off 
and  leave  a  nice  finish.  The  flame  should  not  be  held  flat  against 
the  work.  It  will  take  longer  to  smooth  off  the  work,  and  it  will 
not  have  nearly  as  neat  an  appearance  if  the  flame  is  used  flat. 

Burning-On  Connecting  Links.  The  terminal  poles  should 
extend  up  into  the  links  about  one-third  of  the  way.  The  flame 
should  be  brought  down  into  the  hole  until  the  inner  cone  almost 


Fig.  85.     Assembling  Terminal  Groups 


OXY-ACETYLENE   WELDING 


85 


touches  the  top  of  the  pole,  and  the  pole  fused  and  united  with  the 
bottom  of  the  link  as  quickly  as  possible.  After  a  good  union  has 
been  secured  in  this  manner,  the  burning  bar  should  be  introduced 
and  the  rest  of  the  cavity  filled  up,  Fig.  86.  When  working  on  links 
and  poles  it  is  advisable  to  do  only  part  of  one  pole,  move  to  another 
for  a  few  minutes,  and  then  come  back  to  the  first  for  a  few  minutes. 
This  will  allow  the  work  to  cool  off  slightly  and  will  prevent  breaking 
down  or  melting  away.  When  burning  this  class  of  work,  especially 
if  the  lead  is  old  and  pitted  with  dirt  and  cut  by  acid,  it  is  advisable 
to  increase  the  supply  of  oxygen 
and  use  an  oxidizing  flame 
when  working  down  in  the 
pocket.  This  will  burn  out  any 
dirt  and  will  prevent  the  blow- 
pipe from  puffing  out  when  it  is 
burning  in  the  rare  atmosphere 
that  exists  in  the  pocket. 

Forms  or  Molds.  Small  steel 
frames,  or  molds,  are  found  very 
convenient,  e  s  p  e  ci  a  1 1  y  when 
working  on  terminal  links. 
These  molds  are  shaped  to  con- 
form to  the  work  and  are  placed 
around  it  while  burning.  They 
are  a  great  help  in  preventing  the 
corners  of  the  work  from  break- 
ing down  and  melting  away  and,  in  this  manner,  relieve  some  of 
the  tediousness  of  the  work  and  allow  the  operator  to  work  under  less 
strain,  and  permit  the  work  to  be  done  by  men  who  are  not  skilled 
lead  burners,  but  who  have  occasional  work  of  this  sort  to  do. 


Fig.  86.     Burning-On  Connecting  T.inlp* 


CARBON   REMOVING   BY  USE  OF  OXYGEN 

Methods.  Old  Process.  Up  to  within  the  last  few  years 
the  methods  used  for  removing  the  carbon  from  gas-engine  cyl- 
inders were  very  impractical  and  unsatisfactory.  To  do  this  work 
meant  the  dismantling  of  the  motor,  the  removal  of  all  the  parts, 
and  the  scraping  of  the  cylinder  walls  by  hand.  Because  this 


86 


OXY-ACETYLENE  WELDING 


operation  necessitated  a  great  deal  of  work  it  was  not  done,  in  most 
cases,  until  the  carbon  deposit  became  very  heavy. 

Oxygen  Process.  The  introduction  of  the  inexpensive  process 
of  removing  the  carbon  by  burning  it  out  by  means  of  pure  oxygen 
has  replaced  the  old  methods  and  they  are  no  longer  used.  This 
new  process  is  so  simple,  necessitates  so  little  work,  can  be  done  so 
quickly  and  cheaply,  that  it  can  be  employed  every  few  months  and, 
in  that  way,  keep  the  cylinders  free  from  carbon. 

Carbon=Removing  Apparatus.  Complete  apparatus  for  remov- 
ing carbon  by  means  of  oxygen,  Fig.  87,  consists  of  the  following: 

Carbon-removing  handle  with  flexible  tube 
Oxygen  regulator  with  low-pressure  gage 
One  length  of  high-pressure  rubber  hose 

It  will  be  seen  from  this  list  that  all  that 
is  necessary  for  a  garage  to  have  in  addition 
to  its  welding  equipment  is  the  carbon- 
removing  handle  with  a  flexible  tube. 

Burning  Out  Carbon.  Shut  off  the  gas- 
oline at  the  tank  or  just  in  front  of  the 
carburetor  and  allow  the  engine  to  run  until 
it  has  sucked  the  gasoline  out  of  the  lines. 
Remove  the  valve  caps  and  spark  plugs 
from  all  the  cylinders. 

Turn  the  engine  over  by  hand  until 
the  first  piston  is  at  the  upper  end  of  its 
stroke  and  both  its  valves  are  closed.  Intro- 
duce a/  small  quantity  of  kerosene  into  the 
cylinder  head  by  means  of  an  oil  can  or  a 
piece  of  saturated  waste.  Light  the  kero- 
sene in  the  cylinder,  introduce  the  end  of 
the  flexible  tube  into  the  cylinder  and  allow  the  oxygen  to  play 
on  the  carbon  at  a  pressure  of  about  5  pounds  per  square  inch. 
The  carbon  deposit  will  catch  fire  and  will  continue  to  burn  as 
long  as  there  is  carbon  present.  Of  course,  if  the  carbon  is  depos- 
ited in  patches  it  will  be  necessary,  after  one  patch  has  been 
removed,  to  start  another  by  means  of  kerosene. 

After  the  first  cylinder  has  been  thoroughly  cleaned,  turn  the 
engine  over  by  hand  until  the  piston  of  the  second  cylinder  is  at 


Fig.  87.     Carbon-Removing 
Apparatus 


OXY-ACETYLENE  WELDING  87 

its  upper  stroke  with  its  valves  closed,  and  then  proceed  to  remove 
the  carbon  from  this  cylinder  in  the  same  manner. 

After  all  the  cylinders  have  been  thoroughly  cleaned,  clean  the 
valve  caps  and  spark  plugs  by  scraping  or  by  burning  off  the  carbon 
and  then  replace  them  in  the  engine. 

Notes  on  Carbon  Burning.  Before  burning  out  the  carbon  be 
sure  that  there  is  no  chance  of  gasoline  being  present  which  might 
cause  back-firing  into  the  intake  manifold. 

The  oxygen  pressure  should  not  be  too  high.  Only  enough  oxygen 
should  be  supplied  to  keep  the  carbon  kindled.  Too  much  pressure 
will  waste  oxygen  and  increase  the  cost  of  burning  out  the  carbon. 

Too  much  kerosene  must  not  be  used,  because  there  is  a  chance 
of  the  operator  burning  his  hands  with  the  sudden  burst  of  flame 
that  might  result. 

EXAMPLES  OF  AUTOMOBILE  REPAIR 

Pressed=Steel  Parts.  All  pressed-steel  parts  of  automobiles, 
such  as  frames,  bodies,  fenders,  axle  housings,  tubing,  etc.,  should 
be  welded,  using  a  pure  iron  welding  wire  for  a  filling  material. 

Frames.  Almost  all  frame  repairs  necessitate  a  certain  amount 
of  dismantling  of  other  parts.  The  extent  of  the  dismantling  depends 
upon  the  location  of  the  proposed  weld.  If  the  work  is  to  be  done 
under  the  body,  it  is  best  to  remove  the  car  body.  This  is  not 
absolutely  necessary,  however,  because  the  work  can  be  done  by 
merely  jacking  up  the  body  several  inches  to  give  enough  room  to 
do  the  work,  and  protect  the  body  from  the  heat  of  the  welding 
flame.  If  the  weld  is  to  be  done  close  to  the  radiator,  this  should 
be  removed  so  that  the  solder  will  not  be  melted  out,  Fig.  88.  If 
the  weld  is  about  12  inches  from  the  radiator,  the  solder  can  be 
protected  by  placing  sheet  asbestos  over  the  radiator.  In  this 
connection  it  is  well  to  remind  the  operator  that  it  is  always  advisable 
to  cover  the  parts  of  the  car  near  the  welding  with  sheet  asbestos 
to  protect  them  from  any  possibility  of  the  flame  or  heat  getting 
too  close. 

Jacks  should  be  placed  under  the  frame  and  the  frame  brought 
into  alignment  before  the  welding  is  started;  the  jacks  should  not 
be  removed  until  the  weld  has  been  completed  and  has  become 
thoroughly  cooled. 


88  OXY-ACETYLENE  WELDING 

It  is  always  advisable  to  bevel  the  work  by  chipping.  In  the 
case  of  frames  of  light-weight  pleasure  cars  this  may  be  dispensed 
with  if  the  operator  is  careful  to  penetrate  through  the  thickness 
of  the  material.  All  paint,  dirt,  and  grease  must  be  scraped  off 
next  to  the  weld  from  both  the  inside  and  outside  of  the  frame 
before  the  welding  is  commenced,  to  prevent  dirt  from  being 
incorporated  in  the  weld. 

A  reinforcing  plate  should  be  prepared  about  the  same  thickness 
as  the  frame,  as  wide  as  the  frame  is  high,  and  about  three  times 


Fig.  88.     Radiator  Is  Removed  if  Welding  Flame  Is  Near  It 

as  long  as  it  is  wide.  This  may  be  cut  out  of  sheet  steel  by  means 
of  the  cutting  blowpipe,  Fig.  82,  page  77,  or  by  means  of  a  hack  saw. 
The  blowpipe  is  the  quickest  and  easiest  method,  especially  for 
cutting  plates  for  curved  frames  such  as  are  used  on  pleasure  cars. 
The  weld  will  look  better  if  the  reinforcing  plate  is  welded  on  the 
inside  of  the  frame,  but  in  some  cases  that  is  impossible  without  a 
great  deal  of  extra  dismantling.  It  is  then  allowable  to  weld  it  on 
the  outside. 

The  welding  should  start  at  the  lower  end  of  the  frame  and 
move  upward  as  explained  under  Vertical  Welding,  page  31.    The 


OXY-ACETYLENE   WELDING 


89 


two  flanges  of  the  channel  should  then  be  welded,  starting  at  the 
corner  and   moving  toward  the  edge.     When  welding  the  lower 


•••••I 

Fig.  89.     Badly  Bent  Frame 


Fig.  90.    Frame  after  Heating  with  Welding  Flame  and  Straightening 


90 


OXY-ACETYLENE   WELDING 


flange,  the  work  should  be  carried  on  as  explained  under  Overhead 
Welding,  page  31.  After  the  frame  has  been  welded,  the  reinforcing 
plate  should  be  welded  on  by  welding  the  horizontal  edges  first 
and  the  ends  last. 

The  weld  will  be  materially  strengthened  if  it  is  hammered 
during  the  process  of  welding,  as  explained  under  Hammering, 
page  46. 

The  oxy-acetylene  blowpipe  is  also  very  valuable  in  straightening 

frames  that  have  become  bent  in 
accidents.  A  frame  of  this  sort 
is  shown  before  and  after  straight- 
ening in  Figs.  89  and  90. 

Bodies  and  Fenders.  Bodies 
and  fenders  that  have  been  torn 
can  be  successfully  welded  if  the 
operator  uses  his  best  efforts  and 
is  careful. 

Fenders,  as  a  rule,  do  not 
present  very  much  difficulty  be- 
cause the  break  usually  extends 
to  the  edge.     It  is  advisable  to 
pack   wet   asbestos    along    both 
sides  of  the  weld  to  prevent  buck- 
ling as  much  as  possible,  Fig.  91. 
The  wet  asbestos  will  absorb  the 
heat  and  will  not  allow  it  to  be 
conducted  back   into   the  sheet. 
Bodies  should  be  welded  in  a  similar  manner  when  they  are 
torn.     If  possible,  it  is  advisable  to  bend  the  edges  outward  slightly 
before  welding.     Then,  as  the  weld  is  cooling,  hammer  it  flat  to 
compensate  for  the  contraction  that  takes  place. 

If  a  patch  must  be  welded  in,  it  should  be  prepared  either 
round  or  oval,  or  should  have  rounded  corners  of  large  radii. 
The  patch  should  be  dished  to  compensate  for  the  contraction 
that  will  take  place  when  the  work  cools.  The  hole  in  the  body 
and  the  patch  should  be  trimmed  so  as  to  fit  well.  When 
the  patch  is  ready,  it  should  be  tacked  in  place.  The  welding 
should  be  carried  on  as  quickly  as  possible.  After  the  weld  has 


Fig.  91.    Welding 

along  Weld  Will  Prevent  Buckling 


Torn  Fender.    Wet  Asbestos 
Will  Prevent  . 
of  Light  Sheets 


OXY-ACETYLENE  WELDING 


91 


been  completed,  the  flame  should  be  played  on  it  to  heat  it  evenly. 
As  the  weld  starts  to  cool,  the  center  of  the  patch  should  be  heated 


Fig.  92.     Broken  Front  Axle 


Fig.  93.     Welded  Front  Axle 


Fig.  94.    Crankshaft  in  Crankshaft  Jig  Table  for  Welding 

slightly  so  that  it  will  stretch  easily  and  compensate  for  the  con- 
traction taking  place  in  the  weld. 


92 


OXY-ACETYLENE  WELDING 


Springs.  The  welding  of  springs  should  not  be  attempted 
except  for  emergency  repairs  to  allow  the  car  to  be  used  until  a  new 
spring  can  be  obtained.  A  steel  welding  rod  of  low-carbon  content 


4 


Fig.  95. 


Pre-Heating  Crankshaft  with  Gas 
Burner 


Fig.  96.    Welding  Crankshaft.    Note  that 

the  Pre-Heating  Burner  Is  Used  to 

Assist  the  Welding  Flame 


should  be  used  for  filling  material.  No  attempt  should  be  made 
to  re-temper  the  spring,  because  the  average  garage  is  not  equipped 
to  handle  work  of  that  nature  and,  consequently,  the  spring  is  very 


Fig.  97.     Welded  Crankshaft 


likely  to  be  worse  if  a  poor  job  of  tempering  is  done  than  if  tempering 
is  not  attempted.  It  is  well  to  pack  wet  asbestos  around  the  spring 
next  to  the  weld  to  prevent  the  heat  being  conducted  back  into  the 
rest  of  the  spring. 


OXY-ACETYLENE  WELDING 


93 


Shafts  and  Axles.  Shafts  and  axles  are  alloys  of  nickel,  nickel 
and  chromium,  or  chromium  and  vanadium.  It  is  desirable  to  have 
the  filling  material  of  the  same  composition  as  the  shaft  or  axle, 
but  this  is  practically  impossible.  The  most  suitable  welding  rod 


Fig.  98.     Broken  Malleable-Iron  Rear-Axle  Housing 

that  can  be  obtained  for  this  work  is  one  containing  about  3.50 
per  cent  nickel,  or  one  containing  about  0.20  per  cent  vanadium  and 
0.12  per  cent  chromium.  This  latter  steel  is  more  difficult  to  handle 
under  the  welding  flame,  so  that  most  welders  prefer  the  3.50  per 
cent  nickel  rod. 

Square  shafts,  Figs.  92  and  93,  and  round  shafts,  Fig.  80,  page 
76,  should  both  be  beveled  by  means  of  the  cutting  blowpipe  or  by 
grinding,  and  should  then  be  placed  in  alignment  or  in  suitable 
jigs,  Fig.  94.  A  gas  or  oil  pre-heating  burner  should  then  be  directed 


Fig.  99.     Repaired  Malleable-Iron  Rear-Axle  Housing 

on  the  point  of  welding,  Fig.  95,  and  the  work  heated  to  a  red  heat 
before  welding  is  started.  The  welding  should  then  be  carried  on, 
Fig.  96,  according  to  the  instructions  given  under  Welding  Heavy 
Sections,  page  58.  After  the  welding  has  been  completed  the  work 
should  be  reheated  and  any  straightening  done  that  is  necessary. 


94 


OXY-ACETYLENE  WELDING 


The  weld  should  then  be  heated  up  evenly,  covered  over  with  sheet 
asbestos,  and  allowed  to  cool  slowly.  The  finished  weld  is  shown 
in  Fig.  97. 

Axle  Housings.  If  the  housing  is  of  pressed  steel,  it  will  not 
present  any  particular  difficulty  to  the  welder,  except  that  he  will 
have  to  take  care  that  it  does  not  get  out  of  alignment.  A  pure  iron 
welding  wire  should  be  used,  and  the  work  should  be  prepared  and 
carried  on  as  explained  under  Light  Sheet-Steel  Welding,  pages 
46  to  50 

If  the  housing  is  of  malleable  iron,  Figs.  98  and  99,  it  should 
be  beveled,  placed  in  alignment,  and  then  brazed,  using  Tobin  bronze 

for  a  filling  material  as 
explained  under  Malle- 
able-Iron Welding,  page 
67.  The  work  may  be 
pre-heated  slightly  to  re- 
lieve the  effect  of  expan- 
sion and  contraction,  but 
must  not  be  heated  above  a 
dark  red.  The  operator 
must  be  very  careful  to 
not  bring  the  malleable 
iron  at  the  weld  to  too 
high  a  heat  or  its  mal- 
leable properties  will  be 
destroyed  and  the  hous- 
ing will  be  weak. 

Manifolds.    Pressed- 
steel  manifolds  should  be 

Fig.  100.     Welding  Broken  Flange  on  Manifold  welded    according    to   the 

directions  given  under  Light  Sheet-Steel  Welding,  pages  46  to  50. 
Cast-iron  manifolds,  as  a  rule,  have  only  simple  breaks  to  be 
repaired,  such  as  broken  flanges,  Fig.  100.  These  should  be  beveled, 
and  the  parts  clamped  to  a  flat  surface  to  keep  them  straight.  They 
should  then  be  pre-heated  in  the  vicinity  of  the  weld  by  means  of 
the  welding  blowpipe  before  the  welding  is  started.  After  the  weld 
is  completed  they  should  be  reheated  evenly  and  then  covered 
over  and  allowed  to  cool  slowly. 


OXY-ACETYLENE   WELDING 


95 


Engine  Cylinders.  If  the  water  jacket  is  cracked,  the  crack 
should  be  chipped  out  and  the  surface  of  the  casting  next  to  the 
groove  should  be  cleaned  by  scraping.  If  the  cylinder  is  cracked  in 


Fig.  101.     Water  Jacket  Cut  Away  to  Allow  for  Welding  Cylinder  Wall 

the  head  end,  it  will  be  necessary  to  cut  away  a  section  of  the  water 
jacket  by  drilling  or  sawing,  Fig.  101.  After  the  cylinder  head  has 
been  welded,  the  water-jacket  section  can  be  welded  back  into  place, 
Fig.  102.  Sometimes  it  is  quite  difficult  to  detect  how  far  the  crack 
really  extends,  therefore,  care  must  be  taken  to  be  sure  that  it  is 
chipped  out  its  entire  length. 

All  of  the  plugs  and  other  fittings  must  be  removed  from  the 
cylinders  before  pre-heating.     The  cylinders  should  be  placed  in 


Fig.  102.     Cylinder  Wall  Welded  and  Section  of  Water-Jacket  Replaced 

the  pre-heating  fire  with  the  open  end  of  the  cylinder  upward, 
Fig.  103.  They  may  be  placed  on  a  slant  if  the  crack  is  on  the  side 
of  the  water  jacket;  but  they  must  be  in  such  a  position  so  there 


96 


OXY-ACETYLENE  WELDING 


will  be  no  chance  for  dead  air  to  remain  in  them.    If  this  precaution 
is  not  taken,  the  cylinder  walls  are  very  likely  to  crack. 

The  welding  should  be  carried  on  according  to  the  directions 
given  under  Cast-iron  Welding,  pages  59  to  67.  The  cylinders 
must  be  left  in  the  charcoal  fire  all  during  the  welding.  It  is  even 
advisable  to  keep  the  top  of  the  fire  covered  over  and  to  weld  through 
a  hole  in  the  asbestos  paper,  Fig.  103,  to  prevent  air  currents  from 
striking  the  cylinder  while  it  is  hot.  After  the  welding  has  been 


Fig.  103.    Welding  Cylinders  and  Preparing  Pre-Heating  Fire  for  Cylinders 

completed,  the  fire  should  be  started  up  enough  to  heat  the  entire 
casting  evenly,  and  should  then  be  covered  over  and  allowed  to  die 
out.  The  cylinder  must  not  be  removed  until  it  has  become  cold 
enough  to  be  handled  with  bare  hands. 

Protection  for  Machined  Surfaces.  The  finish  in  the  bore  of  the 
cylinder  will  be  affected  by  the  heating  if  some  means  is  not  used 
to  protect  it.  The  best  protection  that  can  be  used  is  to  coat  it  and 
other  machined  surfaces  with  flaked  graphite  and  oil.  This  can 
be  made  into  a  paste  and  painted  on,  or  the  surfaces  can  be  oiled 


OXY-ACETYLENE  WELDING 


97 


Fig.  104.    Water  Jacket  Plugged  and  Welds  Being  Tested 
Gasoline 


with 


and  the  graphite  dusted  on.  The  latter  method  is  really  the  best 
if  carefully  applied.  The  graphite  must  be  coarse;  the  fine  flake 
will  not  do. 

Testing  Welded  Cyl- 
inders. There  are  sev- 
eral ways  of  testing 
welded  cylinders.  The 
two  most  generally  used 
are  by  water  pressure 
and  by  gasoline.  In  the 
first  method,  the  water 
jacket  is  tightly  plugged, 
filled  with  water,  and 
then  subjected  to  pres- 
sure by  means  of  a  hand 
pump.  The  method  of 
using  gasoline  is  simpler 
and  quicker.  The  water 
jacket  is  plugged  and 
filled  with  gasoline,  Fig. 
104.  If  there  are  any 
cracks  or  leaks  the  gas- 
oline will  work  its  way 
through  and  will  spread 
out  over  the  surface  sur- 
rounding the  crack  or 
leak. 

Crankcases  and 
Transmission  Cases.  It 
is  usually  necessary  to 
remove  the  case  from  the 
car.  But,  if  the  arm  is 
broken  some  distance 
from  the  main  case,  it 
may  be  welded  while  in 
position,  as  shown  in  Fig.  105.  When  welding  in  this  manner,  it  is 
necessary  to  cover  the  parts  near  the  welding  with  asbestos  sheets 
to  protect  them  from  the  flame  of  the  blowpipe.  The  arm  should  be 


Fig.  105.    Welding  Arm  of  Crankcase  without  Dismantling 


OXY-ACETYLENE  WELDING 


pre-heated  slightly  by  means  of  the  welding  blowpipe  before  the 
actual  welding  is  started,  and,  after  the  welding  has  been  completed, 

it  should  be  reheated  to  relieve 
any  internal  strains,  and  must 
then  be  covered  over  to  allow  it 
to  cool  slowly. 

Some  operators  spend  a  great 
deal  of  time  trying  to  keep  the 
bearing  of  the  case  in  line,  and 
while  doing  this  they  allow  the 
rest  of  the  case  to  twist,  so  that 
it  is  necessary  to  take  a  machine 
cut  off  the  edges  in  order  that 
they  may  fit  the  other  half  of  the 
case.  It  is  much  better  to  keep 
the  edges  true  and  dress  up  the 

bearings,  because  it  is  quite  likely  that  the  bearings  will  have  to  be 
trued  up  anyway.  The  case  should  be  clamped  flat  against  two 
straightedges,  but  not  too  tight,  or  the  case  might  crack  from  the 

strains  produced  when  heat  is 
applied.  The  case  should  be 
placed  on  the  welding  table  in 
suchva  position  that  the  welder 
can  work  on  the  outside  and 
smooth  off  the  inside  without 
having  to  disturb  its  position. 

The  most  satisfactory 
method  of  pre-heating  is  to  place 


Fig.  106.     Badly  Broken  Transmission  Case — 
Must  Be  Pre-Heated  All  Over 


Fig.  107.    Lower  Half  of  Crankcase  with  Piece 
Broken  Out — Must  Be  Entirely  Pre-Heated 


Fig.  108.    Upper  Half  of  Crankcase  with  Piece  Broken  Out  and  Missing 

a  gas  burner  under  the  case  and  let  it  burn  without  an  air  blast.    If  an 
air  blast  is  turned  on,  the  case  is  liable  to  become  overheated  and 


OXY-ACETYLENE  WELDING 


99 


cave  in.  In  fact,  unless  there  are  holes  to  allow  some  of  the  heat 
to  escape,  the  case  is  liable  to  become  overheated  with  only  the 
soft  gas  flame.  If  the  case  is  broken  at  one  end,  as  shown  in  Fig.  108, 
it  is  only  necessary  to  heat  the  one  end;  but  it  is  very  necessary  to 
heat  both  sides  of  that  end  to  prevent  warping.  If  like  the  case 
shown  in  Figs.  106  or  107,  it  is  best  to  heat  the  entire  case.  This 
can  best  be  done  by  using  two  gas  burners  so  that  the  heat  will 
surely  spread. 

If  the  case  is  cracked  or  a  piece  is  broken  off,  the  welding  should 
start  at  the  inner  end  of  the  crack  and  move  toward  the  edge  or  corner. 
The  welding  should  be  carried  on 
as  directed  under  Cast  Aluminum 
Welding,  page  71. 

If  a  piece  has  been  broken 
out  and  lost  necessitating  building 


Fig.  109.    Sheet-Iron  Form  to  Back  Up  Section  to  Be  Welded-In 

up  a  section  of  the  casting,  Fig.  108,  it  is  necessary  to  back-up  the 
work  by  means  of  a  piece  of  sheet  iron  bent  to  the  required  shape, 
Fig.  109.  The  welding  should  be  started  at  one  edge  and  should 
move  across  the  space  in  a  line  parallel  to  the  edge.  When  the 
added  material  gets  almost  to  the  opposite  edge,  the  welding  should 
stop,  the  edge  of  the  case  and  the  edge  of  the  new  added  section 
should  be  cleaned,  and  then  the  weld  completed  in  the  same  manner 
as  for  welding  up  a  crack,  Fig.  110,  as  outlined  above. 

COSTS 

The  cost  of  welding  varies  within  wide  limits  for  the  different 
metals  and  the  different  classes  of  work.  It  is,  therefore,  not  possible 
to  give  cost  tables  that  will  apply  to  all  work.  The  costs  given  in 
Tables  II  and  III  are  for  steel  work  under  fair  conditions. 

Measuring  Oxygen  Consumption.  Oxygen  is  supplied 
compressed  to  1800  pounds  per  square  inch,  in  cylinders  containing 


100 


OXY-ACETYLENE  WELDING 


TABLE   II 
Welding  Cost  Table 


Thickness 
of  Metal 
(in.) 

Speed 
(ft.  per  hr.) 

Oxygen 
per  Linear  Foot 
(cu.  ft.) 

Acetylene 
per  Linear  Foot 
(cu.  ft.) 

Cost 
per  Linear  Foot 
Labor  45c 
Oxygen.  .  .  .   2c 
Acetylene.  .  2Jc 

<& 

26 

0.15 

0.14 

$  .024 

A 

22 

0.22 

0.21 

.030 

& 

17 

0.43 

0.41 

.045 

h 

14 

0.68 

0.65 

.063 

i 

Hi 

1.03 

0.98 

.083 

A 

9 

1.84 

1.74 

.13 

1 

7 

3.01 

2.88 

.20 

f 

4| 

6.74 

6.44 

.40 

i 

3 

13.2 

12.5 

.73 

I 

H 

38.7 

37.0 

2.00 

i 

l 

76.7 

72.9 

3.81 

TABLE   III 
Cutting  Cost  Table 


Cost 

Thickness 
of  Metal 
(in.) 

Speed 
(ft.  per  hr.) 

Oxygen 
per  Linear  Foot 
(cu.  ft.) 

Acetylene 
per  Linear  Foot 
(cu.  ft.) 

per  Linear  Foot 
Labor  45c 
Oxygen  ....   2c 

Acetylene..   2jc 

i 

90 

0.34 

0.10 

$  .014 

i 

74 

0.55 

0.17 

.021 

* 

55 

1.16 

0.33 

.040 

a. 

4 

46 

1.91 

0.47 

.060 

1 

40 

2.75 

0.61 

.082 

i* 

33 

4.70 

0.85 

.13 

2 

29 

6.97 

1.06 

.18 

3 

24 

12.3 

1.46 

.30 

4 

20 

19.4 

1.96 

.46 

6 

15 

38.3 

3.04 

.87 

8 

11 

69.7 

4.60 

1.55 

TABLE  IV 
Factors  for  Correcting  Oxygen  Volumes 


Deg.  F. 

Factor 

Deg.  F. 

Factor 

Deg.  F. 

Factor 

100 

0.929 

75 

0.972 

50 

1.020 

95 

0.937 

70 

0.981 

45 

1.030 

90 

0.946 

65 

0.990 

40 

1.040 

85 

0.954 

60 

1.000 

35 

1.051 

80' 

0.963 

55 

1.010 

30 

1.061 

101 


OX Y- ACETYLENE  WKLD-JNti 


100  and  200  cubic  feet.    The  amount  pf  oxygen  im  a;  tyHafe^ 
be  measured  quite  accurately  by  means  of  the  high-pressure  gage 
on  the  regulator.    Most  of  these  gages  are  supplied  with  two  rows 


Fig.  110.     Upper  Half  of  Crankcase  with  Section  Built-in 

of  figures  on  the  dial,  Fig.  111.  The  outer  circle  gives  the  pressure 
in  the  cylinder  in  pounds  per  square  inch,  and  the  other  circle  gives 
the  per  cent  of  oxygen  remaining  in  the  cylinder.  The  latter  set  of 
numbers  makes  the  calculation  very  easy:  e.g.,  if  a  100-cubic  foot 
cylinder  is  being  used  and  the  gage  hand  indicates  73,  there  is  73 


ACETYLENE  CO. 
UVU50-NEWYORK 


Fig.  111.     Dial  of  High-Pressure  Gage  of  Oxygen  Regulator 

cubic  feet  of  oxygen  in  the  cylinder.  If  a  200-cubic  foot  cylinder  is 
being  used,  there  is  200X0.73  =  146  cubic  feet  in  the  cylinder. 
The  amount  of  oxygen  indicated  by  the  gage  reading  is  more  or  less 
approximate  and  depends  upon  the  temperature  of  the  oxygen  in  the 


102  OXY-ACETYLENE   WELDING 

cylinder.  The  correction  factors  given  in  Table  IV  should  be  used 
to  determine  the  volume  of  the  oxygen  at  "standard  temperature", 
60°  F.,  if  an  accurate  measurement  is  required,  e.g.,  if  in  the  case 
given  above  the  temperature  is  50°  F.,  then  the  real  volume  at 
standard  temperature  would  be  146X1.020  =  148.9  cubic  feet. 

Measuring  Acetylene  Consumption.  The  amount  of  acetylene 
in  a  cylinder  cannot  be  determined  by  means  of  the  high-pressure 
gage.  All  the  high-pressure  gage  can  be  used 'for,  in  the  case  of 
acetylene,  is  to  indicate  very  roughly  the  amount  of  acetylene  in 
the  cylinder.  There  is  only  one  method  that  can  be  used  to  determine 
the  amount  of  acetylene  used,  and  that  is  to  weigh  the  cylinder. 
Each  pound  by  weight  of  acetylene  is  equal  to  14.5  cubic  feet.  There- 
fore, to  determine  the  amount  of  acetylene  used  on  a  certain  job,  it  is 
necessary  to  weigh  the  cylinder  before  and  after  welding  and 
calculate  the  volume  of  acetylene  used  from  the  difference  in  weight, 
e.g.,  if  the  cylinder  weighs  217  pounds  before  welding  and  207  J 
pounds  after  welding,  then  (217  -207|)X  1.4.5  =  9JX  14.5  =  137.7 
cubic  feet. 


INDEX 


INDEX 


PAGE 

Acetylene 4 

consumption 102 

cylinders 4 

generators 5 

Adhesion 33 

After-treatment 45,  66,  70,  72,  74,  76 

Aluminum  welding 68 

cast 71 

sheet 69 

Annealing 45 

Automobile  repair,  examples 87 

axle  housings 94 

bodies  and  fenders 89 

crankcases  and  transmission  cases 97 

engine  cylinders 95 

frames 87 

manifolds 94 

pressed-steel  parts 87 

shafts  and  axles 93 

springs 92 

B 

Back-firing 24 

Blowholes 66 

Blowpipe : 7,  16 

how  to  light 23 

how  to  shut  off 23 

inclination 27 

injector 7 

manipulation 28,  44,  63 

position 27 

pressure 7 

Brass  welding 74 

Bronze  welding 74 

Butt  weld . 49,  54 

C 

Carbon  removing  by  use  of  oxygen 85 

Carbon  blocks 67 

Cast-iron  welding 59 

Charcoal  fire 43 

Connecting  apparatus,  instructions  f  or , , 22 


INDEX 

PAGE 

Copper  welding 72 

Corner  welds 50,  54 

Costs 99 

Cutting 10,  76 

apparatus 78 

principle • 77 

Cylinder  welding 49,  54 

D 
Defects  in  welds 32 

E 

Electric  welding 11 

apparatus 13 

arc  welder 12 

spot-welder 11 

Expansion  and  contraction 8,  36,  43,  46,  53,  58,  60,  68 

complex  case 39 

methods  of  handling 37 

simple  case 37 

F 

Flange  weld 49 

Flux 9,  61,  69,  73,  75 

G 

Generators 5 

low-pressure 5 

pressure 6 

Graphite  electrode 13 

H 

Hammering 9,  46,  59 

Holes,  welding  up 31 

Hose..  .  21 


Jigs 47 


Lead  burning 81 

apparatus 83 

M 

Malleable-iron  welding 67 

Metallic  electrode 13 

Metals,  properties  of 34 


INDEX 

O  PAGE 

Overhead  welding  .....................................................  31 

Oxidation  .............................................  32,  43,  59,  68,  72,  74 

Oxy-acetylene  flame  .....................................  8,  24,  44,  69,  73,  75 

Oxy-acetylene  process  .......................  '  ..........................  3 

advantages  ......................................................     3 

Oxygen  ..............................................................  3 

consumption  .....................................................  99 

P 

Penetration  .........................  ..................................  33 

Pipe  welding  .........................................................   56 

Pre-heating  .....................................................  40,  60,  71 

methods  .........................................................   41 

reasons  ..........................................................   40 

Preparation  of  work  for  welding  ................  8,  14,  46,  51,  57,  62,  71,  73,  75 


Regulators  ...........................................................    19 

acetylene  ........................................................   20 

care  .............................................................   21 

cutting  .....  -.  ................................  ....................   79 

operation  .............................  ...........................   19 

oxygen  welding  ...................................................   20 

Reinforcing  welds  ............................  .........................   34 

Re-welding  .....................................................  70,  74,  76 

Rods  ..........  .  ...................................  8,  29,  44,  60,  68,  72,  75 

S 

Spot-welder  ..........................................................  11 

Steel  welding  .......................  .  .................................  43 

castings.  ....  ....................................................  57 

f  orgings  .........................................................  57 

heavy  sheet  ......................................................  51 

light  sheet  .......................................................  46 

Strength  of  welds  .....................................................  9 

T 

Tables 

cutting  cost  table  ............  .....................................  100 

factors  for  correcting  oxygen  volumes  ................................  100 

properties  of  metals  ...............................................   35 

welding  cost  table  ........................  .........................  100 

Tacking  .............................................................   47 

Tank  welding  ...................................................  51,  55;  56 

Tube  welding  ......................................................  51,  56 

V 

Vertical  welding  ......................................................  31 


INDEX 

W  PAGE 

Welding 15 

brass 75 

bronze 75 

cast  aluminum 71 

cast-iron 63 

copper 73 

heavy  sheet-steel 53 

light  sheet-steel , 48 

malleable-iron 68 

sheet-aluminum 70 

steel  castings 58 

steel  f orgings 58 

Welding  processes 1,  63 

electric 11 

old  and  new  methods 1 

oxy-acetylene 3 


LD21-100m-7,'33 


YC   13848 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


